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PLAGUE 



PLAGUE 



ITS CAUSE AND THE MANNER OF ITS 
EXTENSION— ITS MENACE— ITS CONTROL AND 
SUPPRESSION— ITS DIAGNOSIS AND TREATMENT 



BY 

THOMAS WRIGHT JACKSON, M.D. 

MEMBER AMERICAN RED CROSS SANITARY COMMISSION TO SERBIA, IOI5; LATELY 

CAPTAIN AND ASSISTANT SURGEON, U. 8. VOLUNTEERS; LATELY LECTURER ON 

TROPICAL DISEASES, JEFFERSON MEDICAL COLLEGE; MEMBER OF MANILA 

MEDICAL SOCIETY AND PHILIPPINE ISLANDS MEDICAL ASSOCIATION; 

AUTHOR OF A TEXT BOOK ON TROPICAL MEDICINE; DIRECTOR, 

DEPARTMENT OF SANITATION AND EPIDEMIOLOGY 

FOR H. K. MULFORD COMPANY 



WITH BACTERIOLOGIC OBSERVATIONS 

BY 

DR. OTTO SCHOBL 

BUREAU OF SCIENCE, MANILA 



ILLUSTRATED 



PRESS OF 

J .B. LIPPINCOTT COMPANY 



"RCI7I 



COPTKIGHT, 1916 
BY THOliAB WBIUBT JACI80S. M.D. 



MAY 23 1916 
©CLA433197 



THIS BOOK IS DEDICATED BY THE AUTHOR TO 

DR. ALDO CASTELLANI 

REGIUS PROFESSOR OF TROPICAL DISEASES, 
UNIVERSITY OF NAPLES. EMINENT IN MEDICAL 
RESEARCH, MY FRIEND, COLLEAGUE AND COM- 
RADE DURING STRENUOUS DAYS IN SERBIA 






I 



CONTENTS 

PAGE 

Introduction 11 

CHAPTER I 

Its History and Its Extension 19 

History of Plague — The Widespread Dissemination of Plague 
in Recent Years — The Appearance of Plague in Porto Rico, 
New Orleans and Manila. 

CHAPTER II 

The Cause and the Menace of Plague 28 

Causation of the Disease and its Mode of Conveyance — 
Types of Plague — Chronic Plague and Immunity in Rats 
— Flea Conveyance of Plague Bacilli — The Stability of Viru- 
lence of Plague Bacilli — Summary of Facts Concerning the 
Cause and Manner of Extension of Plague. 

CHAPTER III 

Its Control and Suppression 40 

Plague Prevention by Extermination of Rats — General Use- 
lessness of the Rat and Its Enormous Destructiveness, with 
Details of Trapping and Other Extermination Methods — The 
Manila Epidemic, 1912-1914— The First Cases— Unusual 
Character of Plague Cases at Quarantine — Clinical Descrip- 
tion of Two Cases at Quarantine — Inauguration of the Manila 
Epidemic — Directed to Take Charge of Plague Suppression in 
Manila — Plague Fighting Organization — Method of Rat Proof- 
ing and Rat Destruction — Correspondence Between Dr. Jack- 
son and Dr. Heiser, Director of Public Health — Observations 
on Fleas and Their Habits — Conditions of Habitations in 
Manila Favoring Rat Multiplication and Spread of Plague — 
Comparative Statistics on Methods of Catching Rats — The 
Natural Enemies of the Flea — Zoologic Classification of Rats — 
A Collection of Notes Concerning Rat Runs, Rat Nests, Multi- 

5 



CONTENTS 

pie House Infections and Other Data — Sample of Detailed 
Orders Issued Regarding Rat Extermination — Method of Pro- 
cedure of Collecting and Forwarding Rats Suspected of Plague 
Infection to Laboratory — Memoranda in Plague Cases — Letter 
of Warning and Appeal for Cooperation — Bacteriologic Ob- 
servations made During the Manila Plague Epidemic, By Dr. 
Otto School — Notes Concerning the Bubonic Plague in Hong 
Kong, by Dr. David Roberg. 



CHAPTER IV 

Its Diagnosis and Treatment 



165 



Biologic Diagnosis — Necessity for Trained Bacteriologist — 
Bacteriologic Procedure — Non-Biologic Diagnosis — Sympto- 
matology — Pathologic Considerations — Treatment, Conditions 
and Prognosis — Serum Treatment — Symptomatic Treatment 
— Statistical Studies in Mortality — Dosage and Technique of 
Serum Administration — Prophylactic Serum and Anaphylaxis 
— Plague Vaccines. 



ILLUSTRATIONS 

PAGE 

Rat-Proof Structure 48 x/ 

Cleaning and Rat-Proofing in Basement 69 V^ 

Bamboo House Supports not Sealed with Cement 86 *^ 

Materials Must be Moved About in the Search for Rats 93 

A Rat-Infested Plague Interior 95 

Progressive Post-mortem Changes in Rat Cadavers 105 

Plague House 116 

Bamboo House Supports Sealed with Cement 119 

View of House Where Infected Rats Were Found 120 

Animal House 144 



PLAGUE 



ITS CAUSE AND THE MANNER OF 
ITS EXTENSION — ITS MENACE — ITS 
CONTROL AND SUPPRESSION 
— ITS DIAGNOSIS AND TREATMENT 



INTRODUCTION 

The question of the need for new books upon 
medical topics must ever remain undecided, by gen- 
eral agreement, in the medical profession. 

There is no such thing in medical literature as 
an insistent demand from the profession for new 
volumes upon old topics. 

Authors need not hope, therefore, to create the 
impression that they are meeting long-felt though 
unexpressed wants of medical readers in launching 
new books. 

On the other hand, the creator of a new volume 
upon an old subject should seek justification for 
literary paternity in the progressive changes in the 
status of our knowledge of disease, its causes, pre- 
vention, and cure. Such changes are admittedly 
going on with a certain degree of constancy and at 
such a rate of frequency that new presentations of 
old themes are both justified and desirable from 
time to time. 

With this idea in mind and with the desire to 
present, in useful and practical form, a work which 
shall contain at least some unhackneyed material 

11 



12 PLAGUE 

and which shall represent modern studies and a 
record of actual control work done in this justly- 
dreaded disease, the following pages are submitted to 
the medical profession and to sanitarians generally. 

With a profound respect for the laboratory 
worker and his work and with a profound convic- 
tion that to him belongs the greater measure of 
credit for real accomplishment in connection with 
plague up to the present time, I desire to insist that 
the true utility of knowledge gained within labo- 
ratory walls lies in its intelligent application in the 
outer world and that of ttimes this application must 
be made by men who are themselves without ex- 
tended laboratory training. An appreciation of 
principles — with an intelligent ability to accept, to 
appropriate, to apply and, most of all, to refrain 
from entering without due preparation the domain 
of the laboratory worker — is an indispensable req- 
uisite in the equipment of the jDractical sanitarian, 
upon whom must fall the responsibilities of success 
or failure in combating the disease we are now to 
consider. 

During the past fourteen years it has been my 
privilege to observe two epidemics of plague in the 
Philippine Islands. Some of these observations were 



INTRODUCTION 13 

made in the capacity of a military medical officer, but 
my later observations, upon which this report and 
study are chiefly based, were made from the view- 
point of a civil health officer. At different times I 
have been called upon to deal with the disease both 
as sanitary officer and clinician, and from October, 
1912, to July, 1914, 1 had charge of all plague sup- 
pressive measures in Manila. In 1914 I was also 
in charge, as acting chief, of the San Lazaro Hos- 
pitals Division of the Bureau of Health, Manila, 
where all cases of plague are brought, either for 
treatment or autopsy. 

As some of the material which I have collected 
for text-book articles during the past eight years 
bears directly upon the present discussion and pres- 
entation, I have ventured to quote from it, some- 
times without rephrasing, such parts as are accurate 
at the present time. I am also quoting freely from 
the records and from the experiences of my pred- 
ecessors and colleagues in the work in Manila. 

It should be understood that the pathology of 
the disease has been practically omitted from con- 
sideration as out of place in an epidemiologic in- 
vestigation and report. The pathologic side of the 
work during the Manila epidemic of 1912-1914 was 



14 PLAGUE 

covered in a masterly manner by Dr. B. C. Crowell 
and his associates at the Medical School of the Uni- 
versity of the Philippines, and I have no doubt that 
the record of the work done and studies made will 
appear in appropriate form in due time and will 
hereafter be referred to as among the most valuable 
pathologic studies ever made during a plague 
epidemic, on account of their accuracy and com- 
pleteness. 

I have included, as of great value and directly 
related to the epidemiologic phase of this study, 
reports of some of the bacteriologic work done in 
connection with this epidemic at the Bureau of 
Science, Manila, by Dr. Otto Schobl. I am sure 
that the value of his studies as reported in part here, 
with his permission, will be apparent to every care- 
ful reader. I am greatly indebted to him for his 
permission to make use of this portion of his studies. 
Having been in daily touch with Dr. Schobl during 
the year and a half of the continuance of this 
epidemic, I can appreciate to the fullest extent the 
painstaking and accurate character of his work and 
findings, of which the part here presented is by no 
means the greatest. 

I am quite aware of the fact that there are those 



INTRODUCTION 15 

who view with some question the practicability of 
controlling plague by the measures applied in 
Manila, as recited here; but American plague 
workers are likely to meet this unbelief by pointing 
to the accomplished fact, in San Francisco, in Hono- 
lulu, in Porto Rico, as well as in Manila; and be- 
fore long, as we confidently expect, in New Orleans. 
These exponents of the school which contends 
that plague epidemics are little affected by rat-ex- 
cluding, rat-destroying and rat-proofing efforts, be- 
lieve that the waning and disappearance of epidemic 
plague in a given place depend in chief part upon 
the exhaustion of susceptible material among the 
rodent population. However appealing this argu- 
ment may be, it is impossible for its exponents to 
duplicate American results with equal results in the 
cities of China, India, Java and elsewhere, where 
governmental control and adequate financial ability 
to carry out campaigns have been lacking, from 
one cause or another. Wherever our methods have 
been followed, at home and in the insular possessions 
of the United States, we have terminated human 
epidemics of plague and have apparently put an 
end to rat plague in comparatively short cam- 
paigns. So long as this discrepancy in results con- 



16 PLAGUE 

tinues we shall favor the American plan. When 
we review the work and results of Blue and his fel- 
lows of the United States Health Service and the 
officers of the Bureau of Health of the Philippine 
Islands, we find little reason for us to favor a change 
to the expectant plan of waiting for an epidemic to 
run its course. 

While speaking of the Philippine Islands, the 
admirable work of Strong in Manila, covering years 
of study of the immunity problem, and his -danger- 
ous and highly valuable work as a member of the 
Commission which studied the Manchurian epidemic 
of pneumonic plague in 1911, must be mentioned. 

Some years ago I called attention to the fact 
that few, if any, American cities were prepared to 
meet an outbreak of plague with an adequate supply 
of antipest serum and that the preparation of anti- 
plague serum was a neglected or overlooked branch 
of serum manufacture in the United States. Since 
that time, in the midst of a plague epidemic in 
Manila, where, for a time, the supply of locally pre- 
pared (Bureau of Science) serum threatened to 
become exhausted, I looked into the possibilities of 
getting a supply elsewhere and found that, to do so, 
in anything like a reasonable length of time, was 



INTRODUCTION 17 

impossible. Fortunately the threatened serum 
famine did not occur, the local supply in Manila 
proving adequate, although for a few weeks we were 
obliged to make use of a stock of Japanese serum 
which had been on hand for several years. Since 
the warning of some years ago, at which time the 
plague danger was an anticipated one, bubonic 
plague has actually appeared in the United States 
(New Orleans), the cases being sufficiently numer- 
ous to cause grave concern and to call forth the 
utmost repressive efforts of the authorities. The 
possibility of plague appearance in the coast cities 
of the United States, at any time, cannot be disre- 
garded and provision for the treatment of human 
cases, as well as repressive (antirat) measures, is 
imperative. Antiplague serum is not producible 
upon a few hours' notice, nor is it manufactured in 
the United States. In view of present war con- 
ditions the difficulty of securing serum from over- 
seas sources is greatly increased, so that we are well- 
nigh compelled to depend upon home-produced 
serum. In view of the uselessness of drug treat- 
ment it is plainly the duty of national, state and 
municipal authorities to keep on hand a reasonable 
supply of antipest serum to meet any outbreak. 
2 



18 PLAGUE 

Manufacturers of biological products realize that 
the preparations for producing, storing and market- 
ing antiplague serum are expensive and that the 
maintenance of immunized animals and the employ- 
ment of expert serologists call for expenditures 
which are unlikely to be recovered from any demand 
for serum and that, moreover, the government is 
doing and will do all that lies within its power to 
make the serum unnecessary, by excluding plague. 
These are not encouraging conditions to lead Amer- 
ican serum producers to add antiplague serum to 
the list of their products. If, under these adverse 
conditions, any producer of biologic products shall 
undertake to produce and maintain an adequate 
supply of antiplague serum, he will merit credit for 
a truly philanthropic service and will deserve the 
support of governments, national, state and munici- 
pal, as well as that of the medical profession. 






CHAPTER I 

ITS HISTORY AND ITS EXTENSION 

In plague there exists the most intimate relation- 
ship between cause and prevention. We will there- 
fore set forth here, as briefly and concisely as their 
importance will permit, the principal facts related 
to the causation of the disease. Without an under- 
standing of this relationship there can be no rational 
preventive treatment. 

These facts constitute one of the interesting 
stories of modern medicine : the story of the arrange- 
ment and interpretation of certain apparently un- 
related facts, some of them long known to men, in 
the clear light of modern method ; the story of the 
application of analysis, synthesis, logic and experi- 
ment, all leading to the creation of an understand- 
ing which permits us to battle successfully with 
pestis bubonica, one of the most ancient of human 
plagues. 

History. — This disease has an historic interest, 
most engaging and fascinating, which one finds it 
difficult to pass over with mere mention. 

I venture to recall, therefore, that plague almost 

19 



20 PLAGUE 

certainly dates back to the pre-Christian era, the 
earlier record naturally being lacking in sufficient 
accuracy of description to enable us to identify the 
recorded epidemics, definitely and positively, with 
true bubonic plague. 

An epidemic of the second century B.C., as de- 
scribed, seems to have been one of true plague, while 
the pandemic which began in Egypt in the sixth 
century a.d., thence extending to Constantinople, 
Europe and the British Isles, was certainly the dis- 
ease known in modern times as the plague. This 
pandemic, beginning as the plague of Justinian, was 
probably followed by the continuous presence of the 
disease in Europe, marked by many local outbreaks 
and periods of quiescence and extending down 
through the centuries to the period of the Crusades. 
In the eleventh and twelfth centuries the returning 
Crusaders spread the plague widely through 
Europe, which country it ravished from the eleventh 
to the fourteenth centuries, reaching its climax of 
intensity in the " Black Death " of Europe of the 
Middle Ages. The disease thereafter continued to 
devastate Europe, the great population centres, 
Paris and London, suffering especially from its 
visitations and its more or less constant presence. 



ITS HISTORY AND ITS EXTENSION 21 

The Great Plague of London, the last important 
epidemic of the disease in that metropolis, began in 
1664 and lasted five years. With less than half a 
million of inhabitants it is estimated that London 
gave one of every six or seven of her citizens to the 
Black Death during the first year of the epidemic. 
Then followed a remarkable disappearance of the 
disease from Western Europe. The eighteenth 
century was marked by few epidemic appearances 
of plague. 

At the end of the first half of the nineteenth 
century it had practically disappeared from Egypt 
and from European and Asiatic Turkey, formerly 
its favorite haunts. In interior Asia it has probably 
existed for centuries, the non-emigrating character 
of the people limiting and confining its devastations. 

To these centres and to the commercial invasion 
of China, we must probably trace the beginning of 
the present pandemic of plague, which exists to-day, 
a menace to the civilized and uncivilized world. In 
the days of the Crusades a religious invasion of the 
infected centres caused the disease to spread 
throughout Christendom, while in the present day a 
commercial invasion has caused it to spread com- 
pletely around the world. 



22 PLAGUE 

That this is a truth and not a fanciful statement 
is shown by the appearance of plague in the follow- 
ing countries since 1894, when it spread from in- 
terior China. In every case it has followed those 
sanitary lines of least resistance, the paths of 
commerce. 

Extension. — To the eastward, from China, it 
spread to Japan, the Philippines, Australia, the 
Hawaiian Islands, Alaska, California, Mexico, 
Peru and the western coast of South America. To 
the westward, it invaded India, Mauritius, Egypt, 
Suez ports, Eastern, Central and South Africa, 
Mediterranean ports, Great Britain ( Scotland) , the 
West Indies and Brazil. In the last twenty years 
plague has caused millions of deaths, and, during a 
single week in April, 1907, it destroyed more than 
75,000 lives in India, a number about equal to the 
deaths of a year in London during the Great Plague 
of 1665. In contrast with India the rest of the 
world has suffered little during the present world- 
epidemic, but this loss, while relatively small, is 
enormous when translated into lives and dollars. 
The figures for India are simply huge. 

Mortality. — The official lists of deaths in India 
for the last twenty years include some in which the 



ITS HISTORY AND ITS EXTENSION 23 

number of reported deaths per year exceeded one 
million, and it has been estimated that the actual 
number of persons dead from the plague during 
this period approximates 8,000,000. 

It is gratifying to note a marked decrease in the 
total mortality in the reports of the last few years, 
but so long as the annual death list, year after year, 
was measured by hundreds of thousands, rather 
than thousands, the situation could not be consid- 
ered as anything but grave. 

Widespread Dissemination in Recent Years. 
— Without going into statistics deeply we may con- 
sider also the list of countries, states and islands 
from which plague cases have been reported 
officially during the last few years. 

My purpose is to invite attention to the con- 
tinued existence of various plague foci, any one of 
which might serve to extend the infection further, 
were governmental quarantine and public health 
supervision relaxed. 

During August, September, October, Novem- 
ber and December, 1909, plague cases occurred in 
India, Mauritius, China, Japan, Egypt, Turkey, 
Russia, British East Africa, the Azores, Venezuela, 



U PLAGUE 

Ecuador, Peru, Chili, California (two cases), and 
the Hawaiian Islands. 

During the first half of 1910 no very marked 
variation in the distribution of plague occurred, 
cases being reported from practically all of the 
foreign countries just named. 

A year later the situation, so far as the distribu- 
tion of plague cases is concerned, was not greatly 
changed, as may be seen from the following tabu- 
lation, which I have abstracted from the British 
Medical Journal of September 16, 1911. 

India. — Deaths from plague in India during the 
first six months, 604,634. Most prevalent (1) 
United Provinces, 281,317; (2) Punjab, 171,084; 
(3) Bengal, 58,515; (4) Bombay Presidency, 
28,109. Deaths in July, not included above, 8990. 

Hong Kong. — April 24 to August 21, 255 cases, 
194 deaths. 

China. — Since January 1, 1911, plague was re- 
ported in varying intensity in (provinces and 
towns) Manchuria, Peking, Tien-tsin, Chefo, Shan- 
tung, Shanghai, Amoy, Foochow, Swatow, Canton, 
Paklioi and Laichow. 

Indo-China. — At Saigon, in March and April, 
1911, many cases reported. April 17 to May 7. 



ITS HISTORY AND ITS EXTENSION 25 

56 cases; 17 deaths. May 22 to May 28, 37 cases; 
12 deaths. 

Siam. — In Bangkok plague was more severe 
during 1911 than in any previous year. March 15 
to April 15, 33 cases and 29 deaths. 

Java and Sumatra. — In Java, May 25 to June 3, 
105 cases and 62 deaths (one province). In 
Sumatra plague was present, no statistics. 

Straits Settlements. — A few cases, mostly im- 
ported, reported in 1911. 

Japan. — A few cases at Kobe in 1911. In For- 
mosa, from April 2 to April 15, 31 cases; 24 deaths. 

Egypt. — Plague reported from Port Said, 
Suakin (on board ship), Cairo and Alexandria; 
also from 11 provinces. The province of Kena had 
a severe outbreak, May 5 to May 31, 51 cases and 
49 deaths. 

Persia. — Several cases reported from ports on 
the Persian Gulf. 

Turkey in Asia. — A few cases at Muscat, Basra 
and at Port of Jeddah. 

British East Africa. — Kismayu and Port 
Florence reported a few cases in April, 1911. 

Mauritius. — January 1 to April 11, 110 cases 
and 70 deaths. 



26 PLAGUE 

Portuguese East Africa. — Plague was reported 
present at Nahoria in May, 1911. 

Russia. — In the Kirgis Steppe in the Astrakan 
Government in January, 50 cases ; 30 deaths. 

South America. — Plague prevailed during 1911 
in Peru, Ecuador, Brazil, Chile and Venezuela. Xo 
severe outbreak except in Peru, where from Feb- 
ruary to May many cases occurred and died. At 
Libertad, in March, were reported 60 cases and 
23 deaths. 

Appearance of Plague in Porto Rico, New 
Orleans and Manila. — The developments of 1912, 
which most concern us, were the appearance of 
human plague and the discovery of plague-infected 
rats in Porto Rico, Cuba, and the Philippines, and 
the discovery of infected rats in New Orleans. Thus 
the Atlantic cities of the United States were for 
the first time seriously threatened, and the menace 
of the pestilence at home loomed up on our horizon 
with sufficient prominence to excite public concern. 
Our protectors and guardians of the United States 
Public Health Service, to whose watchfulness we 
must credit our prolonged escape from the plague, 
are carrying out all the protective measures at their 
command with the utmost activity. 



ITS HISTORY AND ITS EXTENSION 27 

At the present time we find Porto Rico freed 
from the disease. New Orleans has undergone and 
is still undergoing treatment which may be expected, 
most confidently, to clear it of both human and 
animal plague. 

Of Manila and the work there, much will be 
found in the following pages, but as both rat plague 
and human plague have been absent for more than 
a year we may fairly look upon the epidemic as 
ended. After so long an interval as this any re- 
appearance of plague may fairly be viewed as a 
new epidemic, although it is not humanly possible 
to say that rat plague has entirely and permanently 
disappeared from the city of Manila, as yet. 



CHAPTER II 

THE CAUSE AND THE MENACE OF PLAGUE 

The foregoing facts are quite sufficient to make 
us realize both the possibility and the danger of a 
world-epidemic; a danger which has existed for 
some years and which recently has been especially 
menacing to the United States. 

Causation of the Disease. — Plague is an acute 
infectious epizootic disease, caused solely by Bacillus 
pestis, a bacterial organism. The disease is com- 
mon to man and to a number of the lower animals 
and fowls. 

Prominent among the animals susceptible to 
the disease is the rat, and from this animal, through 
the intermediation of the flea, by far the most cases 
of human plague arise. In California the ground 
squirrel (Citcllus bccchcyi) , a rodent closely related 
to the marmots of Asia, plays a similar role. Of 
the Asian marmots, the tarbagan, a large rodent, 
also commonly suffers from subacute chronic 
plague, which is transmissible to man as an acute 
disease by the fleas which the animal harbors. 

Its Conveyance. — Although conveyance of 

28 



THE CAUSE AND MENACE OF PLAGUE 29 

plague through rats by contact alone — that is to say- 
without the medium of the flea— is denied by mod- 
ern experimenters, it is perhaps wiser and safer 
to consider the disease infectious, inoculable and 
contagious in the common medical meaning of these 
terms, t While it is usually conveyed to man by 
the flea, it may be acquired by the inhalation of 
plague bacilli and, according to some authorities, 
by ingesting or swallowing the bacilli. 

When infection takes place through the diges- 
tive tract, or in other words, by the ingestion of 
bacilli, either the flesh of plague-infected animals 
or fowls, or food superficially contaminated with 
plague bacilli by rats, cockroaches or other carriers, 
serves as the medium. 

Speaking practically, the possibility of infection 
through ingestion is nearly negligible. Indeed, the 
conclusion of Simpson in regard to this possibility 
has been disputed and denied. However, the recent 
occurrence of plague in a cat in Manila, in my own 
experience, observed with me and carefully worked 
out by Dr. Otto Schobl, points strongly to the pos- 
sibility of ingestion plague, the cat in this case ap- 
parently having acquired plague from eating rats 
dead from plague. 



30 PLAGUE 

A full account of this case appears in the bac- 
teriologic observations of Dr. Schobl and in my 
recital of the history of the Manila epidemic. 

Types of Plague. — Plague in man may be of 
several types and these are designated by names 
descriptive of the symptoms or of the regions of 
the body most affected. Thus we have bubonic, 
septicemic and pneumonic types. As both mild 
and virulent cases occur, we also use terms descrip- 
tive of the severity and course of the cases. Thus 
we describe certain cases as ambulant, abortive, 
larval and fulminant. In the rat the evidences of 
plague are less striking in life than they are at the 
post-mortem table. Indeed plague-stricken rats, 
either naturally or artificially (experimentally) in- 
fected, often show very slight evidences of disease 
before death. Chronic plague in rats and a relative 
immunity to inoculation in certain wild rats are 
fairly well recognized phenomena. 

Flea Conveyance of Plague Bacilli. — Both 
male and female fleas convey plague, but the exact 
method of carrying the plague bacilli from diseased 
rats to man, while fairly well determined, is of such 
recent decision as to leave room for further experi- 
mentation. At present it is believed that the flea 



THE CAUSE AND MENACE OF PLAGUE 31 

deposits plague bacilli, at the time of biting, upon 
the skin, by ejecting the contents of its rectum 
and by regurgitation of its stomach contents. At 
least the flea is known to perform these acts at the 
time of biting, and the rubbing or scratching of the 
flea bite with the hand may easily introduce the 
bacilli into the skin at this spot. 1 

The possibility that the flea introduces the 
plague bacilli upon his mandibles, or the skin-pierc- 
ing armament with which he is provided, is also to 
be considered. However, the following facts sup- 
port the first proposition. It has been experi- 
mentally shown that the average capacity of a flea's 
stomach is about one-half of a cubic millimetre and 
that thousands of plague bacilli may be ingested 
by the flea during the biting of a plague-diseased 
rat; that the plague bacilli multiply enormously 
and for many days in the flea's stomach and that 

1 Acknowledgment is hereby made to the Contributors to 
" The Rat and Its Relation to Public Health " by various 
authors, prepared by direction of the Surgeon-General, P. H. 
and M. H. S., for numerous facts utilized in the preparation 
of this article. The particular contributors whose valuable 
chapters have been drawn upon for information are D. E. 
Lantz, C. W. McCoy, D. H. Currie, Carrol Fox, Rupert Blue, 
W. C. Rucker, R. H. Creel, M. J. Rosenau, V. C. Heiser, 
W. C. Hobdy, and J. W. Kerr. 



32 PLAGUE 

the bacilli are found only in the insect's digestive 
tract ; that plague bacilli are regurgitated from the 
stomach and are voided from the rectum with the 
digested blood. 

It has also been proved that almost all varieties 
of rat fleas, under favorable circumstances, will bite 
man and that the most common human flea {Pulex 
irritans) is frequently found upon rats, the flea, 
generally speaking, being much less particular in 
his choice of hosts and in his permanence of resi- 
dence than most insects and ectoparasites in general. 

Of the rat fleas, Pulex pallidus (Lfemopsylla 
cheopis) is common under various names in India, 
the Philippines, Australia, Italy, Brazil and in 
tropical countries generally. It bites both rat and 
man. CcratopliyUus fasciatus, the common rat flea 
of Great Britain and the United States, also bites 
both rat and man. In North America and else- 
where certain other fleas of the genus CcratopliyUus 
have been found upon ground squirrels, cats, rats, 
sparrows and in chicken yards. 

Dog fleas and cat fleas (genus Ctenoeephalus) 
also infest rats, and fleas of other genera are found 
upon mice, rats and ground squirrels rather indis- 
criminately. 



THE CAUSE AND MENACE OF PLAGUE 33 

The significance of these facts in connection 
with prevention of plague is apparent and it is 
plain that our warfare against fleas must be made 
upon all fleas and not upon a single variety. In 
this connection the possibilities of the conveyance 
of plague bacilli by other suctorial parasites and by 
insects which are not parasites, must be borne in 
mind. 

Thus the bed-bug, the louse, the tick and the 
mosquito must be suspected as possible intermedi- 
aries and the fly and the cockroach as possible food 
contaminators. Indeed, laboratory experiments 
have already incriminated bed-bugs, flies and lice 
as potential vectors of plague bacilli. 

Experiment and observation have demonstrated, 
however, that above all other parasites and in- 
sects, the flea is most likely to convey the plague 
germ from rat to man, by reason of his frequent 
excursions from rat-host to human-host, his taste 
for blood from either host, his enormous activity 
and his ability to jump. After a searching inquiry 
into the plague question the Indian Plague Com- 
mission came to the conclusion that contagion plays 
a very minor part in the spread of the disease, less 
than three per cent of human cases being so acquired. 



34 PLAGUE 

This commission also decided that infection is 
conveyed from rat to rat and from rat to man 
solely through the agency of fleas. While these 
conclusions are probably true — and therefore of the 
utmost importance from the standpoint of prac- 
tical prevention — I should question whether the 
other possibilities, however remote, are entirely 
negligible. 

Seasonal conditions may affect the course of 
an epidemic in various ways, (a) By effect upon 
flea prevalence, cold weather greatly lessening the 
number of insects, (b) By effect upon rats, cold 
weather and rains either driving them from over- 
ground to underground, or vice versa, or from their 
principal avenues of travel in cities (the sewers), 
into houses and buildings, (c) By effect upon 
the plague germ, Bacillus pcstis. The resistance of 
this organism is very variable, sunlight and drying 
being its greatest enemies, while darkness and damp- 
ness are its chief allies. So far as temperature is 
concerned, the plague bacillus is not likely to be seri- 
ously affected by natural temperatures, as it is 
not destroyed by heat below 150 degrees Fahren- 



THE CAUSE AND MENACE OF PLAGUE 35 

heit, nor by cold measured by zero Fahrenheit, which 
means that it survives freezing, generally speaking. 

It is probable that the periods of greatest sea- 
sonal prevalence of plague will be found to corre- 
spond generally with increased prevalence of rat 
fleas. During the periods when rat fleas are absent 
or least prevalent, the disease is perpetuated in the 
form of chronic (subacute) rat plague in a small 
number of the rodents. The India Plague Com- 
mission made and verified this observation. 

Cholera epidemics often abate spontaneously 
and this is believed to be due in part to attenuations 
of virulence and changes in the cholera organism 
which may be demonstrated in the laboratory. We 
can hardly hope for such spontaneous abatements in 
plague epidemics, as it has been found difficult to 
attenuate or to intensify cultures of plague bacilli 
permanently in laboratory experiments with 
animals. If it is true that plague epidemics are 
often marked by a preponderance of mild cases 
in the early days and a gradual subsidence of in- 
tensity of the cases as the epidemics wane, we prob- 
ably will have to look to the susceptibility of our 



36 PLAGUE 

patients for our explanation of this phenomenon, 
rather than to variations in the virulence of the 
plague bacilli. If plague bacilli continue to be 
distributed to susceptible people the disease should 
continue with a general stability of virulence. 
Stability of Virulence of B. Pcstis. — Ac- 
cording to Strong, stability of virulence is a marked 
characteristic of B. pcstis, it having been shown by 
him that it is difficult to increase the virulence of a 
very virulent strain or to intensify an attenuated 
one in laboratory animals, working with monk 
rats and guinea-pigs. 2 If his observations are cor- 
rect (and they seem to Correspond with the iincl- 
ings of other observers), the ol't-reeorded occur- 
rence of a preponderance of mild eases of plague 
in the early days of an epidemic and the gradual 
subsidence in intensity of the disease U the epidemic 
approaches its close will have to be explained upon 
other grounds than those of variability of virulence 
by attenuation of virulent strains alone. While he 

""Studies in Plague Immunity." R. P. Strong. Philippines 
Journal ot % Science. June 1 i^O? , No. & Frequent r ef er en ce has 
been made to these studies in the preparation of this article, 
for which acknowledgment is hereby made. 



THE CAUSE AND MENACE OF PLAGUE 37 

admits that B. pestis may become attenuated under 
certain conditions many times during the course 
of an epidemic, it may also regain its virulence, 
he contends, under other conditions. 

With these facts concerning the cause and the 
manner of extension of plague and its menace be- 
fore us, we are in position to approach the problem 
of prevention intelligently, and in the case of plague 
prevention is preeminently preferable to cure, as 
well as decidedly more practicable. 

I think we may be permitted here to sum up 
the problem of plague prevention thus: Without 
fleas, without rats, or without human plague cases, 
there can be no extension of plague, practically 
speaking. 

Therefore the destruction of both rats and fleas, 
the isolation of human plague cases, and the ex- 
clusion from them of all suctorial parasites and in- 
sects, will provide practical security for mankind 
generally. 

A word concerning pneumonic plague may be 
permissible. This form of plague occasionally oc- 
curs in epidemics of great fatality, as, for example, 
the epidemic in Manchuria, North China, ** few 
years ago. 



38 PLAGUE 

The mystery of this outbreak was largely dis- 
pelled by the work of the Americans, Strong, 
Teague and Barber, of the Bureau of Science of 
Manila. 

The occurrence of secondary pneumonia in 
bubonic or septicemic plague is rather common and 
it is likely that such secondary plague pneumonias 
are the starting points of epidemics of pneumonic 
plague, i.e. j of cases of primary plague pneumonia, 
the point of infection being in the respiratory organs 
and the infection being acquired through the inspira- 
tion of plague bacilli. 

The principal prerequisites seem to be an ex- 
tremely moist atmosphere under confined conditions 
and a low temperature ; conditions most unfavorable 
to evaporation and ventilation. Under these con- 
ditions the pneumonic patient sprays plague bacilli 
into the air while coughing and droplet infection 
follows. 

It is therefore apparent that epidemic pneu- 
monic plague is controllable by sanitary and hy- 
gienic measures and, furthermore, that in the ab- 
sence of original cases of bubonic and septicemic 



THE CAUSE AND MENACE OF PLAGUE 39 

plague, with secondary plague pneumonias which 
give rise to primary plague pneumonia in the man- 
ner explained, respiratory plague in epidemic form 
will not occur. 

There is no evidence pointing to the conveyance 
of respiratory plague by insects or other carriers. 



CHAPTER III 

ITS CONTROL AND SUPPRESSION 

Plague Prevention. — At present the most 
promising and the most rationally based phase of 
plague control is that of prevention. The reason 
for this is plainly apparent. If the facts in the 
case are as stated and if the conclusions of the 
Plague Commissioners and students of epidemi- 
ology the world over are correct, to eradicate plague 
we need only to control its carriers. 

To exterminate the rat (and perhaps the mar- 
mot and ground squirrel), to prevent the transpor- 
tation of rats or of infected rat fleas in ships, trains, 
clothing, merchandise and upon the bodies of men 
and animals from the numerous foci or plague 
centres of the world to non-infected localities, is a 
beautiful plan indeed. 

Restricted to single communities, even where 
the intelligence, patriotism, effort and wealth of 
the whole people are enlisted, the undertaking is 
formidable, with obstacles to its execution, and dis- 
couragement must often be expected. Extended 
in its application to the whole plague-infected world 

40 



ITS CONTROL AND SUPPRESSION 41 

it becomes an undertaking seemingly impossible of 
accomplishment. 

Yet we are encouraged to face the situation by 
a glance at what has been accomplished. The 
United States, perhaps, presents the highest ex- 
amples of achievement in the cases of San Fran- 
cisco and Manila. The work in San Francisco is 
too recent and has been too well published to require 
detailed review here. A successful campaign against 
rats in 1907 practically terminated an epidemic of 
considerable proportions well within a year. Be- 
hind this movement, however, were the powerful 
machinery of the Federal Government, money in 
generous amount and a considerably aroused pub- 
lic, resentful of the mismanagement of the 1903 
epidemic, whereby, through pure fear of financial 
loss to commercial interests and by a disgraceful 
suppression of the truth, California was made, per- 
manently perhaps, one of the world's plague centres. 

It has been estimated that the rat population of 
the world is equal to the human population, and this 
estimate does not appear to be unreasonable when 
one considers as indices the destruction of the ro- 
dents in cities by the hundreds of thousands, upon 



42 PLAGUE 

single farms by the thousand, and the wonderful 
procreative powers of the rat. 

Economic Importance of Rat Destruction. 
— It is certain that the economic importance of rat 
destruction upon grounds other than those purely 
sanitary must be impressed upon the public wher- 
ever a rat campaign is to be carried on. 

The absolute inutility of the rat, its enormous 
destructiveness to crops, to merchandise in ware- 
houses and in transit, to poultry, eggs, fruits and 
vegetables, to buildings and furniture, and its in- 
cendiary habits causing annual fire losses of con- 
siderable magnitude, must be emphasized in season 
and out of season. Such items as the value of the 
grain consumed by a single rat per year, as estimated 
by the experts of the Agricultural Department, are 
convincing arguments in the case. At a daily con- 
sumption of two ounces, the ration for a full-grown 
rat, this grain value varies from sixty cents per 
year, for wheat, to two dollars per year, for oat- 
meal, for each rat subsisted. Similar data in great 
variety, relating to direct and indirect losses, are 
available for the purpose of making impressive the 
economic need for rat destruction. 

Accumulated experience from various countries 
and cities shows plainly that there is no single 



ITS CONTROL AND SUPPRESSION 43 

method of rat destruction to be depended upon to 
the exclusion of all others and it also shows that 
without governmental direction and supervision, 
backed by ample authority and the ability and will- 
ingness to expend considerable money, neither 
single nor combined methods will be successful. 
Moreover in the countries where special effort is 
most needed there is often distrust on the part of 
the natives, religious prejudice against the destruc- 
tion of animal life and frequently open opposition 
to the authorities in their efforts to destroy rats. 
The same superstitions and religious beliefs which 
prevent the killing of venomous snakes in India, 
at the annual cost of thousands of human lives, 
operate against most measures of rat destruction 
proposed by the Government. 

Extermination Methods. — The plans and 
weapons of warfare against rats include the use 
of poisons ; traps ; starvation ; rat-proof construction 
of buildings, wharves, bakeries, stables, granaries, 
etc.; the introduction of diseases among the rat 
population by bacterial viruses and the conservation 
of the natural enemies of the rat, such as the cat, 
the dog, the ferret, the mongoose, and certain wild 
animals and birds of the woods and fields. 



44 PLAGUE 

Among the most widely used and most effec- 
tive poisons is arsenous acid boiled with rice, or 
mixed with cheese or cornmeal in the form of a 
paste, or placed upon sweets and fruits. 

Crude phosphorus is chiefly used in similar 
pastes. When mixed with glucose its inflammable 
properties are said to be lost. Its inflammability is, 
of course, a serious obstacle to its general use. 

Strychnine, owing to its bitter taste, is of little 
value in poisoning rats, and when used is best com- 
bined with glucose and one per cent, of cyanide of 
potassium. Soaked wheat, bread or similar food 
is then treated with this mixture and placed where 
rats may eat it. It is said to be eaten readily by 
ground squirrels with fatal effect. It is, however, 
expensive and apt to be taken by domestic fowls. 
Most rat poisons have the disadvantage of being 
dangerous to human life and must be used with 
caution wherever children and ignorant native per- 
sons are about. 

Trapping. — Trapping has been found to be a 
very effective means of rat destruction in cities. 
(See later pages for relative efficiency of traps.) 
Rat traps are of several varieties and are con- 
structed upon various principles. It is sometimes 



ITS CONTROL AND SUPPRESSION 45 

desirable to catch the rats alive and uninjured, and 
for this purpose barrel traps, wire cage traps and 
similar devices are placed in the rat highways. These 
highways are readily discovered in the cities. Con- 
siderable care must be taken to overcome the natural 
caution of the rat, and this includes judgment in 
the use of attractive bait, the concealing and smok- 
ing of traps after handling and perhaps the use 
of some scent, such as the oil of anise, of which rats 
seem to be fond. As a general rule bait should 
differ from the food naturally supplied by the 
locality. For example, about granaries and stables 
fresh animal food should be used for bait, while 
about slaughter houses, meat-markets, fish-markets 
and similar places, where animal offal is abundant, 
the rat should be tempted with vegetable bait. 

Where the circumstances will permit, and this 
is apt to be so for ground-squirrel destruction, the 
burrows may be filled with some asphyxiating or 
poisonous gas. In this manner whole families of 
rodents, and their fleas as well, are destroyed. 

The system is not often applicable in houses, but 
aboard ships it is found most effective, the holds of 
ships being flooded with sulphur dioxide, developed 
by burning sulphur in a special furnace provided 



46 PLAGUE 

with a pumping and piping system for delivering 
the gas at distant parts of the ship. In empty ships' 
holds and elsewhere the simple burning of sulphur 
in open vessels effects the same results, provided 
sufficient sulphur and a sufficient number of vessels 
be used and further provided that the generation 
and confining of gas be sufficiently prolonged. In 
San Francisco harbor, where for more than a year 
nine vessels were disinfected per day, this method 
was adopted as more effective, speedy and econom- 
ical than any other system. It has the disadvan- 
tage, in the case of laden ships, of affording some 
danger of fire. 

Carbon bisulphide has been extensively used in 
California in the burrows of ground squirrels. Its 
fumes, being heavier than air, penetrate the bur- 
rows and promptly poison or asphyxiate all living 
animals and fleas. Absorbent material of some kind 
is saturated with the liquid and placed in the en- 
trance of the burrow, which is then quickly sealed to 
confine the gas. 

It will be seen that, in common with other 
methods of rat destruction, fumigation has a limited 
application and a number of serious objections. It 
is particularly useful aboard ships. 



ITS CONTROL AND SUPPRESSION 47 

The method should never be employed by un- 
skilled persons or those unacquainted with the 
dangers to human life from noxious or asphyxiating 
gases. 

Starving Rats. — The subjects of the starva- 
tion of rats and rat-proof construction may be con- 
sidered together. 

Just as the pig in the Philippine Islands and 
elsewhere in the Orient must give place as a scav- 
enger of human excreta to modern and decent 
methods of waste disposal, so must the rat, a gar- 
bage scavenger the world over, give place to sys- 
tematic garbage collection and removal, with tem- 
porary storage of garbage in covered metal cans 
(rat proof). 

Incidentally it may be mentioned that the effect 
of such measures upon the prevalence of flies and 
the transmission of disease by these insects will be 
very great and very beneficial to the public health. 

Food must be kept from rats and rats must be 
kept from the food. Perhaps the greatest resorts 
of rats are the places where cattle are fed, where 
grain is stored and where animals are killed. 
Slaughter houses, markets, grocery stores, restau- 
rants, bakeries, wharves and warehouses must be 



48 PLAGUE 

regulated by ordinances duly enforced. Much can 
be done with screens of heavy iron wire with a mesh 
of less than one inch. 

When concrete and metal have displaced wood 
and plaster as construction materials; when plank 
sidewalks and refuse piles are no more and when the 
catch basins of sewers have been made rat-proof 
the subsistence problem for the rat will be greatly 
increased in difficulty, and starvation should then 
begin to lessen the rat population, at least in the 
cities. 

Rat-proofing. — Municipal authorities should 
take up the matter of rat-proof construction for new 
buildings and the rat-proofing of old ones by ap- 
proved alterations. In Manila, Hong Kong and 
elsewhere these methods are receiving attention and 
encouraging reports are recorded, more particularly 
with regard to the disappearance of plague in dis- 
tricts so treated than in the disappearance of rats. 
This is most important, for if the rat and his fleas 
are excluded from houses and therefore from in- 
timate association with man (an apparently feasible 
matter through the rat-proof construction of build- 
ings), protection against human plague is in great 
measure accomplished. 



ITS CONTROL AND SUPPRESSION 49 

In Manila the disappearance and continued ab- 
sence of human plague in previously infected local- 
ities goes hand in hand with the introduction of 
systematic rat-proofing in sections where cases of 
human plague occur. 

These measures were first instituted in 1906 and 
plague disappeared from Manila in the same year 
and did not reappear until 1912. 

From 1900 to 1905, $15,000 was paid in rat 
bounties and $325,000 was paid for salaries, wages 
and expenses in rat catching, with little appreciable 
effect upon the number of rats and without causing 
the plague to entirely disappear. It must be ad- 
mitted, however, that practical control of the dis- 
ease was attained during this period. 

Rat-proofing of dwelling houses is less expensive 
than perpetual wholesale rat destruction and is a 
perfectly effective measure against human plague. 
In the suppression of the San Francisco epidemic 
in 1907 rat-proofing was also extensively resorted to. 

The expense of rat-proofing has been generally 
considered as prohibitive, but if the work be con- 
fined at first to the vicinity of infected centres and 
if it be carried on subsequent to rat-destruction in 
corresponding areas the expense need not always be 



50 PLAGUE 

prohibitive — at least in American governed cities. 
The Manila plan of plotting the city into * 'plague- 
infected " areas corresponding with the capture of 
plague-diseased rats and systematically working 
within geographic boundaries in which rat plague 
exists or is likely to spread, as determined by rat 
captures and examinations of the rats for signs of 
plague, has proved to be a good plan. 

To prevent the transportation of rats in ships, 
trains and merchandise is an undertaking of diffi- 
culty as well as of importance. In the case of ves- 
sels it involves an understanding of the manner by 
which rats gain ingress to the ship and the ways of 
preventing them from entering. Few facts are bet- 
ter known, perhaps, than the fact that all ships har- 
bor rats, but, except to the initiated, the extent to 
which some ships are infested is by no means under- 
stood. I have made voyages upon steamships, which 
upon alternate trips carried forage for animals in 
the holds, when the conditions were, to say the least, 
uncomfortable. To have one's state-room taken 
possession of by rats, his clothing carried away, or 
to awake with a rat in his berth are unpleasant, but 
not uncommon, experiences. I personally know of 
a woman, prostrated with sea-sickness, who was 



ITS CONTROL AND SUPPRESSION 51 

obliged to remain in her berth and see four large 
rats disport themselves about her room, and in 
another case, on the same ship, a rat jumped from 
the washstand into the berth of a sleeping woman, 
running across her exposed face and arm. 

In travelling upon small dirty steamers in the 
Orient I have often slept on deck, quite as much to 
avoid the rats and vermin in the state-rooms as for 
better ventilation. In a certain ship in which I 
travelled some of the ship's officers amused them- 
selves by shooting rats with an air-rifle in the lower 
decks, quietly hiding themselves in dimly-lighted 
places and shooting the rats as they crossed the 
lighter spaces. 

In many ships the rat population far exceeds 
the human population. In San Francisco 310 rats 
were destroyed by a single fumigation on a vessel 
of only 260 tons burden. In Bombay 1300 rats 
were destroyed at one time upon a single ship and 
in London 1700 were secured at one fumigation. 

The ease with which rats adapt themselves to 
new environment is shown by the fact that they live, 
when permitted to do so, in cold storage and re- 
frigerating rooms where they grow heavy coats of 
fur for protection against the cold. 



52 PLAGUE 

They gain ingress to ships in three principal 
ways: (1) By coming overside upon gang-planks, 
wharf stringers, etc. (2) By passing along the 
lines by which the ship is made fast to the dock, 
through hawse holes, the rat being an expert rope 
walker. (3) By coming aboard in the cargo. 

By the latter method rats are often brought 
aboard by whole families, their fleas included. Many 
styles of packages such as barrels, bales, crated 
goods, grain in sacks and matting in rolls present 
the rat with abundant opportunity to take pas- 
sage and it is probably thus, as stowaways, that 
rats go to sea in the largest number. Plainly, then, 
the placing of rat- funnels upon all lines from ship 
to wharf, the use of special fenders, the raising of 
gang-planks and even anchorage in the stream will 
not prevent rats from getting aboard ships unless 
cargo disinfection be practised before loading the 
vessel. The ship itself should be fumigated every 
three months if possible. 

Rats are doubtless carried in considerable num- 
bers upon railway cars, both freight and passenger. 

While riding in a street car in Manila in 1908 
I saw a rat run along the window ledge, to the 
mingled fright and amusement of the passengers. 



ITS CONTROL AND SUPPRESSION 53 

The same principles which apply in the case of 
ships apply to cars and trains as well. Grain cars 
in particular should receive especial attention. 

Rat Destruction by the Spread of Rat Dis- 
eases. — The proposal to destroy rats by wholesale, 
by spreading epizootic diseases among them, through 
feeding them bacterial virus, has received much at- 
tention in the last ten years. In 1900 Danysz iso- 
lated a bacillus from field mice suffering an epi- 
demic disease communicable to rats, and great hopes 
were entertained that by means of this method de- 
cided reductions in the rat population would result. 
Indeed the results in Cape Town, South Africa, in 
1901, and in Odessa, Russia, in 1902, seemed to 
justify the hope to some extent and certain observers 
still believe the method to be effective. Experience 
with the Danysz and other organisms has shown, 
however, that introduced epidemic diseases do not 
destroy rats in sufficient number to do much good 
and that nearly all the viruses experimented with 
are more or less unreliable. 

Most of the organisms are apparently related 
to the colon, typhoid or hog-cholera groups. The 
mouse-typhoid bacillus (B. typhi murium) was 
originally isolated by Loeffler in 1899. The para- 



54 PLAGUE 

typhoid bacillus and Gartner's B. enteritidis cor- 
respond closely with the Danysz organism and can 
scarcely be separated culturally. In rodents they 
produce enteritis, sometimes hemorrhagic in char- 
acter, and they are by no means to be regarded as 
harmless for man, as originally supposed. In Japan, 
in particular, serious and fatal cases of diarrhoeal 
disease have followed the accidental eating by man 
of food treated by these bacterial poisons. 

On account of the natural resistance of rats to 
diseases of bacterial causation (plague being the 
most notable exception to this rule), and the clin- 
ical fact that no sufficient death rate among rodents 
is produced by feeding them upon bacterial viruses, 
as well as on account of the dangers to man just 
mentioned, this method of rat destruction is not in 
favor at present. 

Poisoning rats and ground squirrels by chem- 
ical poisons seems to be a preferable method, at 
least equally effective and without most of the dis- 
advantages of uncertainty and danger which attach 
to the bacterial viruses. 

Rat Destruction by Domestic Animals. — 
Concerning the utility of such domestic animals as 
are natural enemies of the rat, in the warfare against 



ITS CONTROL AND SUPPRESSION 55 

the offending rodents, there is considerable differ- 
ence of opinion, based upon varying experiences. 
I leave out of consideration all but the cat and dog. 

It will be found that wherever cats and dogs 
are well housed (indoors) and well fed they are 
apt to be fat, lazy and inefficient. House cats of 
this class will catch mice but will often leave rats 
alone, but half -wild cats, obliged to forage for their 
own subsistence, are often excellent rat-catchers. 
Small, active dogs, particularly of the terrier breeds, 
will often keep houses practically free from rats 
and upon farms they are especially valuable, par- 
ticularly if the construction of buildings is such as 
to permit them to get beneath the floors. The em- 
ployment of these animals will necessarily be con- 
fined to individuals for the freeing of individual 
premises from rats. 

A fact to be borne in mind is one already cited, 
viz. : that cats and dogs sometimes harbor the same 
fleas as the rat. Infected rat-fleas often leave dead 
rats for other animals and, all things considered, 
there are many other objections to the intimate 
house dog and house cat which find comfortable 
resting places impartially upon the beds of adults 
or the cribs of babies and children. 



56 PLAGUE 

Furthermore, my personal observations have 
been such as to cause me to place small reliance in 
the value of the ordinary dogs and cats found about 
habitations wherein the construction is favorable to 
rat-harboring. 

Summary of Prevention for the Com- 
munity. — Before passing to the consideration of 
other matters I would sum up the measures of pre- 
ventive treatment for the community. There must 
be (1) Active warfare against rats and other 
plague-affected rodents and their fleas; (2) Modi- 
fied quarantine — detention or disinfection applied 
to persons, goods and animals; (3) Disinfection of 
cargoes shipped from infected ports; (4) Isolation 
of the sick and proper disposal of the dead ; ( 5 ) In- 
ternational notification between governments of the 
occurrence of plague within their respective terri- 
tories; (6) Lastly, — but we might say first in im- 
portance, — the early recognition of the presence 
of plague and the rapid diagnosis in individual 
cases, both of which are dependent upon laboratory 
workers. 

All of these measures must be fostered, directed 
and aided in every possible way by competent au- 
thority (national if possible), whose officers must 



ITS CONTROL AND SUPPRESSION 57 

be men of great moral courage and of unselfish pur- 
pose. Behind all of this must be generous financial 
support. 

I can best emphasize the importance of the ob- 
servance of the principles I have laid down by in- 
troducing personal experiences in the conduct of 
the antiplague campaign in Manila during 1912, 

1913 and 1914. 

I therefore present here the following account 
of the epidemic, the campaign of suppression and 
the various lessons learned. 

It should not be difficult for the reader to make 
applications of the principles already set forth and 
to confirm by the reported facts the assertion that 
methods based upon these principles are effective. 

If repetitions of any of the foregoing principles 
occur it is hoped that, when taken in connection with 
concrete applications cited, they will not appear as 
redundant. 

The Manila Epidemic of 1912 to 1914. — The 
chronologic facts concerning the development and 
extension of plague in Manila in 1912, 1913 and 

1914 are as follows: 

The disease made its reappearance in Manila, 
after an absence of six years for the human disease 



58 PLAGUE 

and five years for rodent plague, two verified human 
cases having been recorded in June, 1912. 

Preceding the appearance of the first Manila 
cases there occurred upon incoming ships a number 
of cases of plague during the Spring of 1912, de- 
tected at quarantine. Although there is no con- 
clusive evidence which connects these imported cases, 
originating in Hong Kong, China, with the epi- 
demic which broke out in Manila a few months 
later, the fact of their occurrence and recognition is 
interesting enough for us to consider before taking 
up the study of the Manila epidemic. Concerning 
these imported cases Dr. Victor G. Heiser, then 
Director of Health for the Philippines, wrote as 
follows in the Philippine Journal of Science, in 
February, 1914. 

Unusual Character of Plague at Quarantine. — 
It is perhaps worthy of note that, prior to the appearance 
of plague in Manila a number of cases of the disease were 
found on incoming steamers. For instance, on April 6, 
1912, a death was reported on the steamship Zafiro, which 
had arrived the day previous from Hongkong and had 
been in the harbor for twenty-four hours at the time of 
the death. At the medical inspection of the vessel, which 
was made the day previous, no illness was detected. An 
investigation showed that the victim had been on deck on 
the night of April 5, 1912, in apparently good health. 
The next morning, at 6 o'clock, he was found dead in his 



ITS CONTROL AND SUPPRESSION 59 

bunk. The necropsy and subsequent biological findings 
reported by Dr. R. P. Strong of the Bureau of Science 
showed that death was due to pneumonic plague. 

On April 7, 1912, the steamer Loongsang arrived in 
Manila from Hongkong, and the captain reported that a 
death had occurred the day previous in a Chinese member 
of the crew. Upon investigation of this case, the captain 
stated that the man was apparently in good health, but 
that while hauling on a rope he fell over in an apparent 
faint and was placed in a chair and in the course of a few 
hours expired. The necropsy and animal inoculations 
showed that he had died of plague and probably of the 
pneumonic variety. 

Beginning April 7, 1912, the temperature of all mem- 
bers of the crew and of the passengers that arrived in 
vessels from foreign ports was taken with a view to de- 
tecting any possible cases of plague. 

On the arrival of the steamship Taisang from Amoy 
at the Mariveles Quarantine Station at about 6.30 a.m. 
on April 30, 1912, the entire personnel was carefully ex- 
amined and found free from sickness of a suspicious nature 
and from elevations of temperature. Seventy-three per- 
sons were detained to serve a quarantine detention of 
seven days. On the evening of April 30, a Chinese pas- 
senger, aged fifty-one years, was found to have a tem- 
perature of 39° C. with a pulse of 100. He was placed in 
the hospital, but protested vehemently that he was not 
sick. He was carefully watched from the first ; there was 
a slight cough ; physical examination of the chest revealed 
a few rales; smears made of the sputum and stained for 
plague bacilli were negative. On the fifth day, the fever 
still persisted, but the patient stated that he did not feel 
ill and demanded to be released from the hospital. On 



60 PLAGUE 

this day, the expectoration was blood-stained, but no sus- 
picious organisms could be found in the smears nor could 
any physical signs of pneumonia be detected. Further- 
more, there were no palpable glands. On the morning of 
the seventh day, the temperature and pulse dropped and 
the general condition was distinctly worse. The patient 
now admitted that he felt ill. Several hours later, he 
flinched when pressure was made in the right axilla. 
Lymphatic enlargement was now made out, and by the 
evening of the seventh day the bubo in the axilla had in- 
creased markedly in size, the swelling approximating 3 
by 7 centimetres. Glands now became palpable in other 
portions of the body, particularly in the cervical region, 
and a few hours later there were inguinal and femoral 
buboes. The patient became rapidly worse, and died at 
7 o'clock on the morning of the eighth day of his illness. 
At the necropsy, the glands of the right axilla and those 
of the right side of the neck were found enlarged; the 
other lymphatic glands were also enlarged, but to a lesser 
degree. There was consolidation of the lower lobe of the 
right lung, and the spleen was about twice its normal size. 
In brief, the necropsy findings of a typical case of sep- 
ticemic plague were present. Smears from the spleen and 
the right axillary gland showed immense numbers of 
bipolar-staining organisms. Cultures made from fresh 
pieces of tissues and later inoculated into animals gave 
positive results for plague. 

Beginning of the Manila Epidemic. — Pro- 
ceeding with the Manila epidemic inaugurated with 
the two cases referred to as recorded in June, 1912, 
we find that the total number of cases recorded 



ITS CONTROL AND SUPPRESSION 61 

from the time of the outbreak in 1912 until the last 
case in 1914 was 90. (This includes none of the 
imported cases from China which developed en 
route to Manila from Chinese ports.) 

Of these 90 human cases, 76 were fatal and 
autopsies were performed in all instances. Four- 
teen persons recovered. The number of cases of 
animal plague up to July, 1914, was 53. This 
refers only to laboratory-proven cases of rat plague. 
As a matter of fact, hundreds of dead rats, almost 
certainly plague rats, were found in the course of 
rat-proofing operations. 

Although the period covered by this epidemic 
approximates two years, it must not be supposed 
that the progress and extension of the epidemic was 
an uninterrupted or unobstructed one. 

On the contrary, such extension as occurred was 
made in spite of the most active suppressive effort, 
and it is believed that this effort brought about a 
creditable result, as indicated by the accompanying 
record. 

When one considers the favorable conditions 
for the natural spread of plague, both in Manila 
and throughout the Philippine Islands, and realizes 
the interposed difficulties and obstructions, natural 



62 PLAGUE 

and unnatural, geographic, human and domestic, 
which confront us at every turn of the path to 
correction, removal and reformation, our success 
in checking the spread of plague appears as a real 
achievement, especially when contrasted with the 
results of effort during the same period in a British 
city of similar size but a few days' sail from Manila, 
where the cases were numbered by thousands and 
where the infection still persists. 

First Manila Cases. — The first case of plague 
(June 12, 1912) occurred in a resident of Tondo, 
920 Calle Antonio Rivera, and in the light of sub- 
sequent developments it may perhaps be grouped 
with the October cases traced to the Manila Railway 
Company's freight station and yard, as 920 Calle 
Antonio Rivera is but a stone's throw from the 
Manila Railway property. The connection, how- 
ever, is not clear, and, on the other hand, it is not 
wholly inconceivable that the rat epidemic and hu- 
man plague cases at the railway station in October 
may have been secondaiy to this July case. Such 
speculation is fruitless, however, so far as establish- 
ing facts is concerned. 

The second case of human plague occurred 13 
days later, June 25, in a resident of a district some- 



ITS CONTROL AND SUPPRESSION 63 

what removed from the first case, but in the same 
general section of the city. 

Then came a lull of more than a month, until 
August 4, during which time no case of plague 
occurred; or at least none was reported. 

August brought forth five cases on the fourth, 
eighth, fifteenth, and twenty-first days of the month, 
in residents of the Quiapo and Binondo districts. 

These cases were unrelated to the preceding ones 
so far as could be ascertained. 

Another lull of a month, until September 24, 
now occurred without a reported case of human 
plague. During this time, however, the first cases 
of rat plague were discovered, one on August 30 
and two on September 6, all of them in the Quiapo 
district. 

From this time (September 24) on, however, 
human cases occurred at intervals of a few days 
until Christmas Day, 1912, the longest plague-free 
period being one week; the number of cases by 
calendar months being distributed as follows : Sep- 
tember, 3 cases; October, 22 cases; November, 12 
cases; and December, 6 cases. 

Geographic Grouping. — Not until October 21 
was there any apparent geographic grouping of 



64 PLAGUE 

cases indicating a well localized infected centre. 
Upon this date there began the outbreak of plague 
among the employees of the Manila Railway Com- 
pany, laborers at the freight station and yard of 
the company. This freight station and yard is lo- 
cated between Calle Azcarraga, Calle Dagupan and 
Calle Antonio Rivera. The outbreak totalled 17 
human cases, all fatal, and extended into Novem- 
ber. Indeed, the last case traced to this focus oc- 
curred on December 7, 1912. 

During the present epidemic of plague in Manila 
this focus was the only one to which a larger number 
of cases than five could be traced, and in all the 
other instances where multiple cases were traced to 
an infected centre, the foci were all single buildings. 

The locations giving rise to multiple infections 
and the number of cases of plague developing at 
each address, with months of incidence, are as fol- 
lows: Calle San Fernando (804-814), November, 
1912, 4 cases; Calle Teodoro Alonzo (518) , Novem- 
ber and December, 1912, 2 cases; Calle Cabildo 
(Intramuros), November and December, 1912, 2 
cases; Calle Comercio (1028), February, 1913, 2 
cases; Calle Sande (1364), April, 1913, 5 cases; 
Calle Juan Luna (1226), May, 1913, 2 cases. 



ITS CONTROL AND SUPPRESSION 65 

Returning to the Manila Railway outbreak, it 
is necessary to state that a well-defined epidemic 
among rats preceded this outbreak, resulting in the 
death of a large number of rodents (undoubtedly 
from rat plague) . This epidemic was not reported 
by the railroad company until the outbreak of hu- 
man plague had begun. It was then too late to 
identify plague in the dead and mummified rats 
found under floors, platforms and elsewhere, but 
the fact that large numbers of rats had recently 
died here was established by the unanimous testi- 
mony of the employees at the freight station and 
the finding of rat cadavers. 

As stated, the human outbreak here occurred 
upon October 21, and fifteen cases developed within 
8 days. 

This indicates an extensive desertion of fleas 
from plague rat cadavers and an attack upon hu- 
man beings, after a fasting period, on the part of 
the fleas, of several days. The human outbreak 
at the station and the death of a large number of 
rats at the same place, just previous, correspond to 
a nicety and establish to a moral certainty the con- 
nection necessary to explain the epidemic. 

After the railway epidemic of human plague, 



66 PLAGUE 

cases continued to occur through November and 
December, without apparent relation to each other, 
except in the following instances, which have already- 
been mentioned: 

Four cases under one roof on Calle San Fer- 
nando (November 12, 13, 16 and 22) ; 2 cases in 
one house on Calle Teodoro Alonzo (November 26 
and December 2) ; and 2 cases in the same house 
on Calle Cabildo (Intramuros), November 23 and 
December 11. 

These multiple cases will be referred to else- 
where. 

The other cases during October, November and 
December were apparently sporadic and unrelated, 
either to the other human cases or to the few scat- 
tering cases of rat plague discovered from time to 
time. Without doubt, however, all were actually 
related to preceding cases of rat plague, i.e., to un- 
discovered rat cadavers, dead from plague and 
deserted by infected fleas. 

In the following plague houses (see list of cases) 
dead rats were actually found, although the ad- 
vanced degree of desiccation and mummification 
defeated the biologic determination of the cause of 



ITS CONTROL AND SUPPRESSION 67 

death: 518 Calle Teodoro Alonzo; 973 Calle Azcar- 
raga; 282 Estero de Binondo. 

In other plague houses the recent finding of 
dead rats was alleged by the occupants, but rather 
too indefinitely to record positively. 

A study of the maps and lists showing the local- 
ities in which cases of rat plague had been found up 
to this time (December 26, 1912), in connection 
with the location of plague houses, was much less 
suggestive than a similar study of the lists and maps 
covering the cases of 1913. 

However, the existence of concurrent rat plague 
and human plague, in corresponding sections of 
Manila, had been well established already by bac- 
teriologic studies of captured rats, made at the 
Bureau of Science. 

Of nearly equal weight was the observation con- 
cerning the two epidemics, rat and human, at the 
Railway Station, which I have already described. 

The year 1912 closed, then, with a recorded total 
of 50 human cases and 7 verified cases of rat plague. 

January, 1913, saw but a single case of human 
plague. This occurred on January 24, just a month 
from the last previous case, that of Christmas Day. 



68 PLAGUE 

During this month no case of rat plague was 
reported. 

In February, 3 human cases occurred and in 
March, 4 cases were recorded. 

Early in March, 1913, cases of rat plague began 
to occur in the Tondo district in a section lying be- 
tween Manila Bay and the Estero de la Reina and 
extending northward from Calle Moriones. This 
was a new district for rat plague and as the cases 
increased in number we were able to foresee and 
predict the appearance of human plague in the same 
district, which in point of congestion of population, 
poverty of its residents and in the matter of dilapi- 
dation of its light material houses and shacks, is 
about the worst locality in Manila. 

From March 22 to September 20, 1913, all the 
cases of human plague, 11 in number, occurred in 
the midst of this district. During the same period 
25 cases of rat plague were reported from the same 
section, and a glance at a map of this part of Tondo 
instantly shows the relationship existing here be- 
tween rat plague and human plague. 

This relationship is additionally emphasized by 
referring to the memoranda concerning certain over- 
crowded houses, in the midst of the rat plague dis- 



I* 

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ITS CONTROL AND SUPPRESSION 69 

trict, where multiple human cases occurred. (See 
memoranda in re 1226 Calle Juan Luna and 1364 
Calle Sande.) 

The human cases in April were 5 in number, all 
originating in the same house, and the May cases 
numbered 4, two of which occurred in the same 
house. 

It may be explained, in passing, that two cases 
of human plague, discovered in Malolos, 25 miles 
from Manila, on March 23 and March 26, respec- 
tively, were definitely traced to the same house in 
Manila, number 12 Calle Aguila, Tondo, both pa- 
tients having lived in the basement of this house 
until within 48 hours of the development of the 
disease. These persons were unrelated and were 
two of a large number of people who lived in a tene- 
ment at this address. Both patients were detected, 
while still alive, in Malolos, where they were living 
in different and widely separated houses. One of 
the patients died in Malolos but the other one was 
brought to Manila by train and died at San Lazaro 
Hospital. Fortunately no infection was transferred 
to Malolos by these two persons. In this connec- 
tion it is interesting to note that no other cases have 
been reported from outside of Manila, except the 



70 PLAGUE 

small outbreak in Iloilo in the southern islands, 
where the antiplague work was successfully directed 
by Dr. Carroll Fox. Concerning this outbreak, 
Dr. Heiser, then Director of Health for the Philip- 
pines, writes as follows (Philippine Journal of 
Science, February, 1914) : 

Plague in Iloilo. — In Iloilo, a case suspicious of 
plague was reported on July 5, 1912, and this diagnosis 
was subsequently confirmed by the laboratory. It oc- 
curred in the person of a Chinaman who was reported to 
have come from Bais, Oriental Negros, but later inves- 
tigation showed that he had been a resident of Iloilo at 
least since February, 1912. The next case was reported 
August 18, and the last case, September 17, 1912. There 
was a total of 9 cases. All of the cases were confined to 
two houses. During July, August, September, and Oc- 
tober, 1146 rats were caught in the vicinity of the houses 
in which the human cases had occurred, along the water 
front, and in the places which were regarded as suspicious, 
but in not a single instance was an infected rat found. 

Directed to Take Charge of Plague Sup- 
pressive Measures. — Upon my arrival in Manila 
from the United States, on October 23, 1912, I 
received orders from the Director of Health to take 
charge of all plague suppressive measures in Manila 
and I remained in charge of this work continuously 
until July 11, 1914. 



ITS CONTROL AND SUPPRESSION 71 

Plague Fighting Organization. — The plague 
fighting organization was composed of three Amer- 
ican Sanitary Inspectors and from ten to fifteen 
native Assistant Sanitary Inspectors of the Bureau 
of Health, rat catchers and laborers of the Bureau 
and laborers of the City of Manila supplied by the 
Department of Sanitation and Transportation. The 
combined force varied in numerical strength from 
100 to 150 men and was usually divided into three 
parties, distributed in various parts of the city ac- 
cording to the local indications and needs from time 
to time. 

After the invasion of Tondo by rat plague we 
made special effort to rat-proof the light material 
houses of that section, in the course of our cleaning 
operations, by the closure of the open ends of bam- 
boo timbers with cement and with tin cans, in the 
manner shown in photographs herewith. In addi- 
tion to this, special attention was given to the repair 
of broken cement work, and hundreds of Bureau of 
Health orders, verbal and written, were issued to 
owners, at my request, in the rat plague districts. 

The number of houses in which bamboo timbers 
were closed by cement or tin exceeded a thousand. 

In addition to these means, the very important 



n PLAGUE 

matter of depopulating the insanitary basements 
of the light material houses in squares where plague 
has occurred was given attention, with the result 
that hundreds of families were moved from these 
insanitary and dangerous ground-floor rooms to 
quarters well above ground and measurably removed 
from the rats, which roam over the ground from 
house to house, foraging for food under kitchens 
and in ground-floor storerooms, tiendas and eating 
places. The fish packing factories afford them 
abundant food and a number of cases of plague 
have occurred adjacent to these fish-drying estab- 
lishments. 

Rat-proofing and Rat Destruction. — While 
it is frankly admitted that rats may not be com- 
pletely exterminated by poisoning and trapping, the 
statement, so frequently repeated of late, that de- 
structive measures really increase their number, is 
unwarranted and unsustained by facts, at least in 
Manila. It seems to be the common practice for 
disbelievers in trapping and poisoning to array the 
methods of rat-proofing and rat destruction as 
alternative policies, whereas everyone practically 
familiar with the work in such cities as Manila — or 
even in the United States — knows that there is often 



ITS CONTROL AND SUPPRESSION 73 

no choice permitted. Rat-proofing is highly desir- 
able, permanent in its results, and in every respect 
the " method of election." On the other hand, it is 
entirely inapplicable at certain times and in certain 
localities where poverty, lack of interest of property 
owners, and ofttimes lack of interest and of money 
on the part of municipalities, absolutely preclude its 
immediate application. It is therefore unfortunate 
that the statement, that rat poisoning and trapping 
are ineffective, either in controlling plague or in 
reducing the numbers of rats, is circulated. It may 
be shown easily, by the daily records, that within a 
few weeks after extensive rat poisoning and trap- 
ping (with the breaking up of nests) is pursued in 
a given locality, the rat catch drops in the most 
decided manner. 

Individual premises may be practically cleared 
of rats by continued intelligent rat catching and 
poisoning, and while the normal rat birth-rate may 
keep pace with the normal rat death-rate it will not 
keep pace with the normal death-rate plus the poi- 
soning and trapping death-rate in any given locality, 
provided that the poisoning and trapping, with the 
destruction of nests, be intelligently and continu- 
ously carried out. 

Rat-proofing and rat destruction, then, should 



74 PLAGUE 

not be contrasted as alternative procedures or 
policies. Both are valuable and each has a proper 
place. In communities non-infected with plague 
and unexposed to infection it will probably be found 
that rat-proofing, carried out in connection with the 
repairs of old buildings and the erection of new 
ones, will meet the requirements. On the other 
hand, in cities exposed to plague infection or 
already infected, rat destruction is bound to be 
necessary for years to come. 

In emergency, the removal of people from in- 
timate relationship with rats (so far as is possible), 
as practised recently in Tondo district, Manila, 
will often have to take the place of rat-proofing; and 
rat destruction and expulsion will be found, in the 
last analysis, to be the methods upon which success 
or failure in fighting plague during epidemic time 
will depend. 

In tliis connection I quote correspondence which 
passed between the Director of Health and myself 
in 1913. 

Upon March 22, 1913, I directed the following letter 
to the Director of Health: 

Sir: I have the honor to state that Estaban Masibac, 
aged twenty-two, laborer, who died at 140 Perla of bu- 
bonic plague, slept upon the ground floor of this house 
upon a bamboo bed. All these basement dwellers in this dis- 



ITS CONTROL AND SUPPRESSION 75 

trict now infected with rat plague are in considerable 
danger. 

The roving rats which wander over these ground sur- 
faces from house to house come into pretty close contact 
with these basement dwellers, and it would appear that 
they visit the upper stories of the houses rather infre- 
quently, unless food is stored there. Upon the ground 
they forage upon the food dropped there by the residents 
of the houses. 

I would like to have authority to order the vacation 
of these basement rooms which are almost invariably unfit 
for human habitations. 

I look upon this measure as an important one at this 
threatening time and believe it should be enforced in every 
square or block where plague rats have recently been 
found. If this authority is granted it will be used 
judiciously. 

Very respectfully, 

[Signed] T. W. Jackson, 

Medical Inspector in Charge of Plague Suppression. 

Upon March 24 I received the following letter 

of authorization: 

Sir: Confirming my verbal instructions of yesterday 
I have to request that, in accordance with the recom- 
mendation contained in your letter of March 22, that on 
account of the danger of the spread of plague in the dis- 
trict in which plague has appeared extensively, the base- 
ment dwellers in blocks, or squares, in which plague has 
been found, should be ordered to vacate. 
Very respectfully, 

[Signed] Victor G. Heiser, 

Director of Health. 



76 PLAGUE 

Upon November 26, 1912, five dead rats were 
reported from the U. S. Army Commissary Ware- 
houses on the Pasig River near the Malecon. They 
were found dead by workmen there and were thrown 
into the river by the finders and thus, unfortunately, 
examination for plague was prevented. 

Upon November 27, a cat, known to have caught 
and eaten rats recently at the same place, was re- 
ported to be sick. I took the cat to the Bureau of 
Science where she was observed until she died, three 
days later. 

At autopsy, typical bubonic plague (cervical) 
was disclosed, and several guinea-pigs inoculated 
from the spleen and bubo died from the same dis- 
ease. A guinea-pig, inoculated from a swab intro- 
duced into the cat's rectum, also died from plague 
(see report of Dr. Schobl) . 

Four kittens, recently born of this plague cat, 
were observed for two weeks but showed no sign of 
the disease. 

Subsequently about 80 rats were caught at these 
warehouses and in the vicinity, but none of them 
showed post-mortem signs of plague. The Medical 
Department, U. S. Army, then took up the matter 
of rat catching on all military reservations in Manila 



ITS CONTROL AND SUPPRESSION 77 

and in all buildings thereon, but no more oases of 
animal plague were discovered. 

Fleas and Their Habits. — In " Observations 
Upon the Bionomics of Fleas Bearing Upon the 
Epidemiology of Plague in Eastern Java,'' by 
N. H. Swellengrebel, Ph.D., published by the gov- 
ernment at Batavia, Dutch India, in 1913, some in- 
teresting facts, developed by study and experimen- 
tation, are presented. Some of these facts have a 
bearing on the plague problem in the Philippines, 
for it should be borne in mind that certain climatic 
similarities and racial similarities pertain commonly 
to the Javanese and Filipinos and their respective 
countries. 

While we are not prepared at present to make 
general application of the Javanese findings to the 
Philippine Islands, for lack of parallel or confirma- 
tory studies in the Philippines, we may state some 
of the conclusions of the Java workers with pro- 
priety, and we may also point out similarities in the 
construction of certain Filipino and Javanese habi- 
tations in their relation to rat harboring. 

Swellengrebel, in Java, noted the number of 
fleas per rat, dealing with Xenopsylla cheopis (the 
commonest rat flea in Java) almost exclusively. 



78 PLAGUE 

This flea, it will be remembered, is also the common 
rat flea of India, the Philippines, Australia, Italy, 
Brazil and tropical countries generally, being vari- 
ously known as Loemopsylla cheopis, Pulex pal- 
lidas, P. brasiliensis, P. philippinensis, and (in 
Italy) P. murinus. 

It would not be unreasonable, therefore, to ex- 
pect to find at least some of his observations ap- 
plicable to the Philippine Islands. 

Swellengrebel failed to find Ctenocephalus canis 
(dog flea), C. felis (cat flea) and Ceratophyllus 
fasciatas (the common rat flea of the United States 
and Europe) upon Javanese rats. In attempting 
to determine the normal flea census he found that 
field rats, and field rats caught indoors, as well, 
generally carry fewer fleas than house rats and that 
the number of fleas per house rat varies in different 
districts from .02 per rat to 2.3 or 4 per rat and that 
this variation is not invariably constant with the 
presence or absence of rat plague. Concerning the 
question whether or not a high flea census may in- 
dicate rat plague, Swellengrebel offers the reason- 
able opinion that there is little doubt that plague in 
rats increases the number of fleas per rat above 
normal and that, consequently, a sudden or marked 



ITS CONTROL AND SUPPRESSION 79 

increase in the number of fleas per rat, without a 
known normal cause, indicates increased rat mor- 
tality and probably rat plague. 

As to the influence of temperature and humidity 
on the hatching of larvae, he concludes from experi- 
mentation that the duration of development of the 
egg varies under various hygrometric conditions, the 
general rule being, " the lower the humidity the 
longer the development period.' ' 

As to the influences of temperature and humidity 
upon the transition of larva to imago he finds that 
if humidity diminishes, a smaller number of larvae 
reach the adult stage; and also that a saturated 
humidity (in artificial cultures), causing condensa- 
tion of water in the substratum, is very fatal to 
larvae. He offers the thought that this, perhaps, 
explains why only small numbers of fleas are found 
on field rats which live in holes in rice fields which 
are necessarily damp, especially in the rainy season. 

His experiments to determine the duration of 
life of fasting fleas were made with laboratory-bred 
fleas which had never fed on blood and with fleas 
which had already sucked blood. 

The duration of life was variable, but of those 
fleas already fed with blood three-quarters (%) 



80 PLAGUE 

perished within 10 days and the remainder lived 
from ten to twenty days, only one-tenth, however, 
surviving for 13 days, if moist conditions were main- 
tained. High temperature was determined to be an 
unfavorable condition. 

If from these findings one should attempt to 
predicate or predict the extension of plague in 
house rats — based on flea prevalence — and this with 
relation to climatic conditions, we should be led to 
the conclusion that the rainy season, with its greater 
humidity, would be quite the most favorable time 
of year for rat plague extension in Manila and, 
upon the contrary, that the hot dry season through 
its unfavorable influence upon flea breeding would 
be the least favorable season for rat plague in 
Manila. 

The hot months of 1913 did not bear out this 
reasoning, however, for during these months rat 
plague was at its height. 

That increased prevalence of human plague has 
not gone hand in hand with increased prevalence of 
rat plague in Manila, may be explained, I feel sure, 
by the activity of our efforts to destroy rats and to 
remove the people from close relationship with them. 

Another factor of possible explanation of the 



ITS CONTROL AND SUPPRESSION 81 

greatest prevalence of human plague in Manila dur- 
ing the late rainy season of 1912 (October), is the 
fact that rats are certainly driven above ground 
into houses and therefore into closer relationship 
with man by heavy rainfall and the consequent 
flooding of their subterranean homes. 

It appears, therefore, that the seasonal explana- 
tion of greater plague prevalence, rat or human, is 
susceptible of several interpretations and I feel sure 
that in countries like the Philippines seasonal varia- 
tions in heat do not suffice to rid the rats of fleas dur- 
ing any months of the year. If, then, conditions of 
rainfall serve to drive the rats above ground and 
indoors during certain months, it would be reason- 
able to expect more human plague from closer re- 
lationship of rat and man, — provided that no special 
measures were carried out. 

Such, however, is not invariably the rule, if sta- 
tistical studies are to be taken as evidence, and so 
we are reminded that generalizations for countries 
of different climates and seasons are not wholly 
reliable. 

Rat breeding, as well as flea breeding, is in- 
fluenced by climate, but as the reproductive activity 
of the rat is most retarded by cold weather — an 

6 



82 PLAGUE 

unknown condition in the Philippines — and as the 
climate of Manila is fairly equable so far as heat 
and cold are concerned, the only factor which needs 
to be considered is that of rainfall. As already men- 
tioned, rainfall doubtless serves to drive rats above 
ground and so, to a certain extent, away from their 
nests in burrows and underground. 

Their well-known adaptability to changing con- 
ditions, however, permits them to house themselves 
comfortably above ground when driven out of these 
burrows and holes. 

Javan Observations. — The following conclu- 
sions were reached by Dr. J. J. van Loghem in a 
report upon " Some Epidemiological Facts Con- 
cerning the Plague in Java" (published by Civil 
Medical Service in Netherlands India-Batavia, 
1912) : 

1. In plague-infected villages, as distinguished from 
plague-free villages, there exists a con>iikrable mortality 
among house rats. 

2. Rats in plague houses and plague quarters have 
repeatedly died from plague. Fresh plague rats appear 
more often in the houses adjoining plague houses than in 
the houses themselves. 

3. The house rat exists even in the immediate vicinity 
of man. 

4. The ordinary parasite of the house rat is Xcnop- 



ITS CONTROL AND SUPPRESSION 83 

sylla cheopis, which experimentally is known to choose 
man as a host when starving. 

5. Fresh plague rats have repeatedly been found to 
harbor a great number of fleas. 

6. Virulent plague bacilli have been demonstrated in 
the stomachs of such fleas. 

Concerning the prevention of plague by improv- 
ing the native dwellings, the same observer says: 
" Obviously an increase in the distance between man 
and rat becomes an important factor as a means of 
preventing the disease.' ' 

Conditions of Manila Habitations Favor- 
able to Rats and Plague. — As shown by our own 
experiences in Manila, this end, the separation of 
rats and men, is not obtainable by destruction of 
rats by poison, traps and rat catchers. Rats dying 
of plague in their nests furnish the greatest danger 
to man. The plague problem, therefore, where rats 
are already infected, from the stand-point of direct 
prophylaxis, is the problem of dwellings. It was 
from this stand-point that we attacked the problem 
in the Tondo (Manila) campaign in 1913. 

Manila Verification of Javan Observa- 
tions. — Having in mind the experiences of the 
plague investigators in Java during the recent epi- 
demics there (1911-1912), we sought, from the 



84 PLAGUE 

time the Manila outbreak occurred, to verify some 
of the findings of the Java investigators, at least 
with special reference to the nesting of rats in close 
proximity to human beings and the consequent ex- 
posure of these persons to the infected fleas which 
desert the rats dying from plague in these nests. 

Not until rat plague invaded the special district 
of Tondo, in Manila, in March, 1913, did the oppor- 
tunity present itself. Theretofore the Manila cases 
had generally appeared in houses of the so-called 
" hard material districts," where house construction 
is entirely unlike that with which the Java workers 
dealt. With the invasion of Tondo, however, the 
Java and Manila conditions became similar. I 
quote the descriptions of Javanese house construc- 
tion from the report of Dr. J. J. Van Loghem, 
" Some epidemiological facts concerning the plague 
in Java," Eatavia, 1912. 

The Javan Village House. — In substance, he 
says that the Java village house, as a general type, 
is a one-storied structure with its roof sloping to 
the front and back, i.e., with its ridge parallel with 
the front and back aspects of the building. It is 
not elevated above the ground by supports or pali- 
sades and has no separate floor, the earth serving as 
the floor. 



ITS CONTROL AND SUPPRESSION 85 

The outer frame is of strong bamboo poles and 
the inner frame is also constructed of bamboo. 
These bamboo timbers are perforated at various 
points to permit of framing with other pieces of 
bamboo and for the entrance of pegs, etc. 

The roofs of these houses are often made of tiles, 
but at times the familiar thatched roof is seen. In 
both cases the supports or rafters are bamboo poles. 
The principal piece of furniture is the " bale bale," 
or bedstead, usually made of bamboo, except in the 
houses of the well-to-do. Small storerooms are 
often located in the houses, and stables are some- 
times built against them. In many cases the family 
provisions are kept in the house and the cattle are 
housed here as well. 

Manila Light Material Houses. — If, now, 
we turn our attention to the average Tondo 
(Manila) light material house it will be apparent 
that the description given for the Java village house 
fairly describes the Tondo house, except that the 
Philippine house is commonly elevated 2 metres 
or more above the ground upon bamboo supports 
(see photographs). The basement is usually en- 
closed in a manner similar to the principal room of 
the Java house and the basement room may fairly 



86 PLAGUE 

be compared, structurally and in the matter of its 
floor, with the one-story Java house. In the Manila 
house, however, the floor of the upper room takes 
the place of the roof of the Java house and like it 
is supported by bamboo timbers. 

Here, then, in our enclosed basement story, we 
have a practical replica of the one-storied Java 
house. 

Here, also, the principal piece of furniture is 
often a bamboo bed, practically identical with the 
Java " bale bale," if we may judge from photo- 
graphs. 

In the Java houses the favorite nesting places 
for rats were found to be the interiors of horizontal 
bamboo pieces of the roof, house frame and bed- 
stead 

The rat usually gains entrance by gnawing 
through the natural partitions between the bamboo 
sections near the outer end of the pole. Our Manila 
photographs show both the natural open ends of 
such timbers and the rat-gnawed perforations in the 
partitions. 

In Java, rats also nest in the thatched roofs, as 
they occasionally do in the Philippines. 

Nest Materials. — The materials utilized for 






I 

lmujjjiiJiii.-iiuiim:.a'jir!' uimwiniii 




BAMBOO HOUSE SUPPORTS NOT SEALED WITH CEMENT. NOTE HOLES GNAWED IN BAMBOO 
ENDS. RATS FREQUENTLY MAKE NESTS IN THESE HOLLOW BAMBOO RAFTERS. 



ITS CONTROL AND SUPPRESSION 87 

nests by rats in Manila and Java seem to be iden- 
tical also. Straw, dry leaves and pieces of cotton 
are mentioned in the Java reports. The same ma- 
terials and additional ones will be found mentioned 
in our reports upon nests. 

The presence of food was also noted in the 
bamboo nests in Java and we often find articles of 
food in our Manila nests. 

Dr. Korn, P. H. Service, and the writer 
(T. W. J.) investigated a good many of these bam- 
boo house-timbers and we not only found such evi- 
dences of rats as food, rat fasces and nest materials, 
but in one case a rat was actually driven out of a 
bamboo nest by introducing a long thin strip of 
wood. The evidence of similar conditions then is 
complete. 

We also duplicated the experiences of the Java 
workers in finding dead rats inside of the bamboo 
house timbers in close proximity to patients sick 
(or dead) with plague (see memoranda in the case 
of Esteban Masabik, of 140 Calle Perla, March 22, 
1913). 

Very extensive rat destruction and cleaning 
operations, covering a large portion of the city of 
Manila and including all sections where cases of 



88 PLAGUE 

rat plague or human plague developed, were under- 
taken and this work was carried on without inter- 
ruption for about two (2) years. City laborers to 
the number of 60 to 150 were used and the work was 
supervised by Sanitary Inspectors Brantigan and 
Searcy, of the Bureau of Health. During a part 
of the time a flying column of 50 men, under Sani- 
tary Inspector Hunniecutt, was detached from the 
main party and employed at placing rat poison. 

The total amount of accumulated dirt removed 
from houses and yards approximated 5250 tons (for 
17 months ending November 1, 1913). 

Without doubt this general cleaning campaign 
and the removal of this enormous accumulation of 
dirt and rubbish was of great value as an antiplague 
measure. 

The rat catch will always be found to depend 
upon several factors, viz.: the number of persons 
employed; the number of traps and portions of 
poison placed; the location of the operations and the 
length of time a given locality is trapped, poisoned 
and cleaned. The variety of baits and poisons will 
also affect the results. 

In addition to these factors certain others are 
found to operate in reducing the rat catch, as, for 



ITS CONTROL AND SUPPRESSION 89 

example, weather conditions and the occurrence of 
Sundays, holidays and the days just preceding and 
following holidays. 

Upon rainy days and the days just mentioned 
the rat catch almost invariably falls off. 

From statistics collected by me in connection 
with this work, Dr. V. G. Heiser, then Director of 
Health for the Philippine Islands, published the 
following memorandum in 1914. As it is a correct 
transcript of my records I introduce it here in its 
entirety. 

Comparative Statistics in Rat-catching Methods. 1 
— With a view to ascertaining which type of rat trap was 
most effective and also the average number of rats that 
are caught by a given number of poisoned baits that are 
set out, statistics were kept during the antirat campaign 
in Manila. The ratio maintained in catching rats with 
two types of traps is indicated in the following table, a 
perusal of which will show that for the three months ended 
June 30, 1913, there were 120,565 spring or snap traps 
set and that for every 100 of this type of trap set there 
were caught 6.9 rats. During the same period there were 
47,075 wire cage traps set; the total number of rats 
caught was 339; which gives 0.72 rat caught for each 
hundred traps set. For the quarter ended September 30, 
130,627 spring or snap traps were set and 9,753 rats were 

1 Reprint from the Public Health Reports, Vol. 29, No. 6, 
February 6, 1914. 



90 



PLAGUE 



caught, which gives 7.47 for each 100 traps set. During 
this period 40,621 wire cage traps were set and 395 rats 
were caught, which gives 0.97 rat caught for each 100 
wire cage traps set. 





Quarter ended June 30 


Quarter ended Sept. 30 


Kind of trap or poison 


Number 
set 


Number 
of rats 
caught 
or poi- 
soned 


Per 

cent. 


Number 
set 


Number 
of rats 
caught 
or poi- 
soned 


Per 

cent. 


Spring or snap traps . . 

Wire cage traps 

Poison bacon, rice, or 
coconuts 


120,565 
47,075 

166,237 


8,377 
339 

1,216 


6.9 
.72 

.731 


130,627 
40,621 

177,309 


395 
216 


.12 







Quarter ended — 




Number of rate: 

Caught by dogs 

Killed with clubs and other weapons 
Found dead from other causes 



No accurate record was kept of the number of each 
kind of rat bait set. Only the total of all was recorded. 
Bacon or coconut with strychnine and rice with ar- 
were used. For instance, for the quarter ended June 30, 
1913, there were 166,237 poison baits set in new territory 
and the rats found poisoned average for each 100 baits 
0.72. During the next quarter there were 177,309 baits 
set in territory that had been worked over, and only 216 
rats, or 0.12 rat per 100 baits, were killed. From the 
foregoing it appears that the rat poison ranks lowest in 
efficiency but perhaps highest in economy. In view of the 



ITS CONTROL AND SUPPRESSION 91 

fact that the original cost of the cage trap is many times 
more than that of the spring trap, and the cost of main- 
tenance is very high, it will be apparent that the spring 
trap is by far the more economical as well as more 
effective of the two. 

Generally speaking, however, the number of rat 
catchers engaged and the location of their operations 
has the largest influence upon the total catch of rats. 
For the fiscal year July 1, 1912, to June 30, 1913, 
inclusive, the total catch was 55,101 rats (Manila 
only) ; to December 1, 1913, 79,676. 

The most natural explanation of the general 
correspondence between the highest rat catch and 
the highest incidence of human plague would be 
upon grounds of greater activity in rat catching 
effort at times of greatest plague prevalence, but 
from the inauguration of general systematic rat 
catching there was no cessation of effort, even dur- 
ing the abatement of plague, and in consequence 
this explanation does not apply strictly. 

It is true, however, that whenever plague oc- 
curred in districts theretofore free from the disease, 
rat catching was pushed vigorously in the surround- 
ing localities. 

Making due allowance for all the factors men- 
tioned I am impressed with the probability, amount- 



92 PLAGUE 

ing almost to certainty, that the catch of more than 
79,676 rats definitely affected and checked the 
spread of plague in Manila in 1913; and I £m of 
the opinion that systematic and wholesale rat 
catching, carried out in the most economical man- 
ner possible, should be persisted in indefinitely, at 
least until plague disappears, wherever the disease 
occurs. 

Efforts to prevent the spread of plague to the 
provinces of Luzon, by way of the railways, were 
successful and the present measures employed, 
freight inspection, the fumigation of packages sus- 
pected or likely to contain rats, and the similar treat- 
ment of freight cars showing signs of rats, should 
be continued. In a few cases these measures have 
driven rats out of both packages and cars and the 
animals have been killed by the sanitarians on duty 
at the station. 

The matter of water transportation was entirely 
within the control of the authorities in charge of 
inter-island quarantine affairs. 

Rat catching in Manila was systematically per- 
formed and all rats captured were turned over to 
the Bureau of Science for examination for plague. 

When plague foci were discovered the localities 



ITS CONTROL AND SUPPRESSION 93 

were trapped and poisoned both circumferentially 
and centrally, with a view to preventing the dif- 
fusion of infected rats throughout the city. 

Rat-proofing. — The theoretic desirability and 
superiority of " out building " the rat, over all other 
methods of rat suppression, is admitted. The ap- 
parent impracticability of actually rat-proofing 
Manila at the present time and our inability to 
starve the animals out, justify the other and less 
permanent measure, viz.: rat catching. However, 
I heartily favor and urge the most complete and 
thorough-going rat-proofing of buildings actually 
infected with human or animal plague, in all cases. 
The building ordinances of Manila already provide 
for rat-proof construction in all new buildings 
erected. 

With a view to cutting off the food supply of 
the rat, more than 1100 orders upon householders, 
to provide covered garbage cans, were served in the 
district of Tondo alone. 

The open ends of bamboo timbers in more than 
2300 houses were closed, either by cement or tin 
cans, during 1913. 

Theatre Disinfection. — All the cinemato- 
graphs and theatres in the city were disinfected upon 



94 PLAGUE 

repeated occasions by spraying with petroleum and 
cresols, with a view to destroying fleas and prevent- 
ing plague infection. 

Attempts at deception and concealment of 
plague patients, upon the part of members of their 
families, were numerous, but with the close scrutiny 
of death certificates and dead bodies exercised at all 
health stations it is believed that all cases were 
recognized. 

One case of extremely careless diagnosis oc- 
curred. A death certificate was furnished by a local 
native doctor who certified the cause of death to be 
" uterine hemorrhage." Suspicion arising, an 
autopsy was ordered and a pronounced case of 
bubonic plague was disclosed postmortem. Xo evi- 
dence of uterine hemorrhage, except slight men- 
strual signs, was found. 

The destruction of infected fleas in plague 
houses is of course the primary object of the disin- 
fection by spraying, which is thoroughly carried out 
in every house where a case of human plague or rat 
plague appears. The method is a simple one and 
consists in spraying a mixture of cresols (2 per cent. ) 
and kerosene (98 per cent.) over all surfaces of the 
house, floors, walls, underlying ground, furniture 



ITS CONTROL AND SUPPRESSION 95 

and the spaces above ceilings, etc., using the mixture 
liberally and securing a general surface distribu- 
tion. There is no doubt of the toxicity of this mixt- 
ure to all fleas and bed-bugs which it reaches, and 
it is undoubtedly an effective measure in rendering 
an infected house safe. All of the instances of 
multiple house infections, where the cases recurred 
after disinfection, in Manila, have been in houses 
where, for one reason or another, the recommended 
structural rat-proofing has been postponed or where 
it has not been done. Thus, on Calle San Fernando 
the sequence of the four cases (their progress by 
days and in consecutive houses) is explained by the 
travel of rats through efficient rat runs present in 
the walls and ceilings, rather than by the passage of 
fleas through partition walls, from uncommunicat- 
ing house to house. 

So also at Calle Cabildo, where the superstruc- 
ture of the house was a veritable sieve, there was a 
series of communicating double walls. 

At the house on Calle T. Alonso a similar con- 
dition existed, but here the two cases which occurred 
may have been synchronously infected, or nearly so, 
previous to disinfection of the premises. 

At Calle Comercio, where six days elapsed be- 



96 PLAGUE 

tween two cases, the rooms and building were piled 
full of merchandise, defeating immediate disinfec- 
tion, that is, efficient disinfection, until all the mer- 
chandise was moved and the rooms were emptied. 

At 1364 Calle Sande, Tondo, where 5 cases 
originated, the infections were undoubtedly almost 
synchronous and no infection occurred after disin- 
fection of the house, while at 1226 Calle Juan Luna, 
Tondo, the two cases were plainly infected at about 
the same time and this previous to disinfecting the 
premises. 

Guinea-pigs as Indicators of Infected 
Houses. — The following experiment shows strik- 
ingly the necessity for disinfecting houses where 
human or animal plague cases have occurred. 

Upon December 17, 1912, Dr. O. School, of the 
Bureau of Science, and myself, placed two healthy 
guinea-pigs, free from fleas, in a wire trap cage in 
the house at No. 4 Calle Barraca, a few hours be- 
fore the house was disinfected, a patient with plague 
from this house having died within the preceding 
twelve hours. The cage containing the guinea-pigs 
was placed exactly where the patient had slept upon 
the floor, as indicated by the other tenants of the 
house. Disinfection was delayed for a few hours 



ITS CONTROL AND SUPPRESSION 97 

and the guinea-pigs were left in the house for one 
day. Upon December 21 one of the guinea-pigs 
died from typical bubonic plague — anatomically and 
bacteriologically positive — other inoculated experi- 
mental animals also developing the disease. 

Other guinea-pigs placed in plague houses on 
Calle Cabildo and Calle San Fernando, after dis- 
infection of the premises, failed to acquire plague. 

Natural Enemies of the Flea. — It was ob- 
served during the studies in Java that certain 
natural enemies of fleas exist and operate against 
their laboratory cultivation and their natural re- 
production. 

Ants of several varieties, large and small red 
ants and small black ones, were found to be very 
antagonistic to fleas, both in the larval and adult 
states, destroying them actively. 

Fleas in the laboratory were found to be affected 
with mites, with a resultant high mortality among 
the insects. The same parasites were not found 
upon wild fleas. On account of the prevalence of 
mites upon the laboratory fleas certain experiments 
concerning the transmission of plague were vitiated. 

The activity of ants in attacking and disposing 
of rat cadavers found in our antiplague work in 



98 PLAGUE 

Manila was frequently brought to my attention. 
We invariably included an attack upon ants in 
treatment of houses known to harbor, or suspected 
of harboring, plague rats. The combination of 
kerosene and cresols, elsewhere referred to, was 
found to be perfectly satisfactory in the destruction 
of ants; assuming, of course, that the necessary 
procedure of exposing the ants, by the moving of 
merchandise, boards or other protecting materials, 
was performed, so that contact, by spraying the in- 
secticide mixture, was secured. 

Activity of Fleas. — It was also observed dur- 
ing the Java studies that the rat flea, while rather 
lazy, may and does cover distances of five metres 
and that he sometimes covers eighteen centimetres 
at a single leap. 

In addition to this, of course, there must be con- 
sidered the possibility of his falling considerable 
distances. 

Zoologic Classification of Rats. — The mat- 
ter of accurately, systematically and scientifically 
cataloguing and classifying rats is one of great diffi- 
culty and is not to be undertaken by anyone but a 
trained naturalist. However, some of the notes we 
have at our disposal, gathered from many sources, 



ITS CONTROL AND SUPPRESSION 99 

may be set before the reader. It is extremely diffi- 
cult to find exact correspondence of statement in 
the various classifications offered by writers upon 
plague and rats. 

Dr. Lantz gives the following brief classification 
in his section of the publication, " The Rat and Its 
Relation to Public Health." 

Order: Rodentia. 

Family: Muridce. 

Genus: Mus. 

Species are many, but only three or four are cosmo- 
politan. 

Cosmopolitan species : M us rattus — black, brown, and 
roof (Alexandrine) rat; Mus decumanus — gray, barn, 
wharf, sewer, and Norway rat. 

Mus rattus has many varieties known through- 
out the world and these are named according to color 
and habitat. 

In addition to the names given in Lantz's classi- 
fication, we constantly see reference to the black 
house rat, the brownish-gray rat (Mus Aleooan- 
drinus), the ordinary ship rat, the field rat, etc.; 
terms descriptive of habitat and appearance being 
very loosely applied. Little account is taken, by 
many, of the well-known variations in the coloration 
of rats due to climate and season and of the well- 



100 PLAGUE 

recognized aptitude of the rat for living in-door 
or out-door according to circumstances of food sup- 
ply, weather, etc. The " sawah " rat of Dutch 
India, implicated in the prevalence of plague there, 
was formerly considered a variety of Mus decu- 
manus, but is now described as a field variety of 
Mus rattus. So too, varieties of Mus decumanus 
are frequently named according to alleged geo- 
graphic origin, habitat, color and habits, viz. : sewer 
rat, brown rat, Norway rat and migratory rat. 

The inevitable confusion bound to arise from 
such loose classification is obvious. 

Another genus, Gunomys (Nesokia) , implicated 
in plague, is represented in India by two species 
and by at least one (an undetermined one) in Java, 
some confusion existing in the matter as yet. Mem- 
bers of this genus are described as large, rough- 
coated rats which live both as house rats and field 
rats. In India the Plague Commission reported 
specimens of this genus as particularly susceptible 
to plague. 

In the Philippine Islands no specimens of 
Gunomys have been observed, but M. rattus and 
M. decumanus are both present and numerous and 
both are subject to plague, as shown by the presence 
of the disease in specimens examined. 



ITS CONTROL AND SUPPRESSION 101 

In view of the unreliability of the points of dif- 
ference in rats usually given as identifying data, 
such as the number and location of the mammas, the 
variations in color and the peculiarities of the foot- 
pads, the Javan observers depend upon the con- 
formation of the skulls for the determination of 
genera, the skull of M. rattus being oval and arched, 
that of M. decumanus more closely approaching the 
square and rectangular conformation, and that of 
Gunomys being broader, higher and longer than 
either. 

In M. rattus the prominent borders which sep- 
arate the parietal from the frontal surfaces of the 
skull are oval; in M. decumanus they are parallel 
or slightly divergent; in Gunomys they are lyre- 
shaped. 

M. rattus M. decumanus Gunomys 

I 



To determine these differences the heads of the 
rats are cut off, the tissues desiccated by antif ormin, 
or by boiling and stripping. 

From experiences in Porto Rico, Creel, of the 
U. S. Public Health Service, concludes that M. 



102 PLAGUE 

norvegicus (decumanus), while essentially a bur- 
rowing animal and not addicted to climbing or 
swimming, is nevertheless quite capable of doing 
either. He was found to burrow in the hardest 
earth to a depth of two and one-half feet and to 
pass through all kinds of wood, soft brick and lime 
mortar, probably by gnawing. 

The black rat and Alexandrine rat (M. rattus) 
in Porto Rico, according to the same observer, do 
not burrow at all, but can climb and jump in ex- 
pert manner, and are the species found in the rural 
districts, remote from houses. He found that all 
varieties of rats may swim, from ships to the shore, 
distances of from one-fourth to one-half mile, but 
that they lack the sense of direction and probably 
do not land from ships naturally in this manner 
(Public Health Reports, No. 9, February 28, 1913) . 

The female decumanus is a prolific breeder and 
brings forth larger litters than the Mus rattus 
female. 

Mus decumanus is generally conceded to be 
larger and more ferocious than Mus rattus. For 
this reason he drives the smaller rats to the upper 
floors, the decumanus species generally living near 
the ground. He is a burrower and is rarely found 



ITS CONTROL AND SUPPRESSION 103 

in the upper stories of buildings. Decumanus is 
known as a wharf rat, but is rarely trapped on ships 
on the Pacific Coast, according to the observations 
of Surgeon Simpson of the U. S. Public Health 
Service (Public Health Reports, April 11, 1913). 
According to the same observer, Mus rattus is the 
commonest ship-borne rat. He also states that the 
black rat and the roof rat (Aleocandrinus) , both 
varieties of M . rattus, differ chiefly in color. They 
live in upper floors, between ceilings, in walls and 
roofs and are remarkable climbers as well as being 
expert rope-walkers and wire-walkers. On account 
of their natural wariness and caution it is not always 
easy to induce them to enter or approach traps. 

The photographs introduced were taken under 
my direction in Manila in 1912, 1913 and 1914. 
Some of them show the character of the house con- 
struction in Tondo District, Manila, where plague 
flourished in 1913. Others illustrate methods of 
rat-proofing bamboo timbers in houses of light ma- 
terial. These end openings were either closed by 
introducing cement or by placing tight-fitting tin 
cans over the ends of the bamboo rafters. 

There are many interesting memoranda, gath- 



104 PLAGUE 

ered and made in connection with our antiplague 
work in Manila, especially concerning the location 
and construction of rat nests found by our laborers ; 
the materials used and the fabrication of the nests. 
Memoranda giving details of rat catching and rat- 
proofing are also presented and notes showing the 
location of dead rats found in relation to dead hu- 
man bodies of plague victims. 

Notes concerning cases of multiple house in- 
fection are also presented as being of possible in- 
terest. 

The Javan studies in 1911 and 1912 establish 
the fact that it is possible to form a fair judgment 
as to the length of time a rat has been dead, up to 
ten or twelve days, from the condition and appear- 
ance of the rat cadaver, both as to decomposition and 
drying. A series of 50 rats was studied. It is to 
be understood that the conditions under which these 
observations were made were tropical conditions. 
They would be fairly comparable with summer con- 
ditions in America, but should not be followed too 
closely at other seasons of the year. In my own 
experience I have observed that ants are likely to 
attack the cadaver early and to obscure the deduc- 
tions by their destruction of the body. 










9 





PROGRESSIVE POST-MORTEM CHANGES IN RAT CADAVERS. THE NUMBERS 
INDICATE THE NUMBER OF DAYS AFTER DEATH 



ITS CONTROL AND SUPPRESSION 105 

Days after death Appearance 

First to third day. ... .Distention of the abdomen, in- 
creasing. 

Second to third day. .Loosening of hair by gentle pull- 
ing. 

Third to fourth day. Loosening of the epidermis by 

gentle pulling. 

Third to fifth day . . . Perforation of abdominal wall with 

collapse and disappearance of 
distention. This perforation 
may result from bursting of ab- 
dominal wall, or through anus, 
vulva or thorax. 

Fourth to sixth day.. Moist shrinking of the body. 

Swarming of maggots. Spon- 
taneous shedding of tufts of 
hair. 

Fifth to eighth day .. Drying of body. 

Eighth to twelfth day . Complete dryness and rigidity. 

Photograph (after Publications of the Civil 
Medical Service in Netherlands, India) shows the 
progressive postmortem changes in rat cadavers, the 
numbers indicating the number of days after death. 

A Collection of Notes Concerning Rat 
Runs, Rat Nests, Their Location and Other 
Data. — Attention is invited to the following collec- 
tion of notes concerning rat runs, rat nests and their 
locations and other data collected by the various 
working parties under the direction of Sanitary 



106 PLAGUE 

Inspectors Brantigan, Renner and Kennard, of 
Manila. 

Special attention has been given to the finding 
and destroying of rat nests, and in this connection 
please note that during the month of May, 1913, 
one party of workmen (20 men) under Inspector 
Brantigan, killed by hand 511 rats out of a total of 
1319. This means that many nests were broken 
up and that much breeding was interfered with. 
In June, 1913, two parties (40 men) killed 772 
rats by hand out of a total of 3019. 

This work occurred in Tondo District in con- 
nection with extensive cleaning and moving oper- 
ations. 

At 1279 C. Sandejas 2 7 rats were found in 
a nest at the foot of a cluster of bamboo trees, be- 
tween the trunks. Nest was made of leaves. 

At 728 C. Velasquez, Tondo, 12 rats were driven 
from a burrow underneath a thick cement floor by 
formaldehyde gas delivered in the burrow through 
a rubber hose. This burrow was in sand and the 
rats came out about ten minutes after the flow of 
gas began. All were killed or captured and two 
or three died from the effects of the gas. 

2 C. is abbreviation for Calle, the Spanish term for street. 



ITS CONTROL AND SUPPRESSION 107 

On October 27, 1912, two of the rat terriers 
belonging to the Bureau of Health caught 192 rats 
in one storeroom at the Manila Railway Station, in 
38 minutes. At various times they have killed from 
10 to 25 rats at a single location, in connection with 
the cleaning and moving work done by the laborers. 
The dogs caught about 600 rats in all. 

On March 11, 1913, 27 rats were caught by 
laborers at 202 Calle Concha. They were nesting in 
straw covers which had been removed from bottles. 

On March 11, 1913, 13 rats were found be- 
neath a pile of loose tiles at 203 C. Sardinas. The 
nest was made of fibres from coconut shells and 
straw. 

On March 13, 1913, 12 rats were found among 
stones scattered in a shallow pile on the ground at 
C. Conservador (interior). Nest was made of rice 
chaff and small pieces of cloth. 

On March 15, 1913, 9 rats were caught at 1353 
C. Anloague on the ground floor beneath a pile 
of boards. Nest was made of coconut fibre and 
shavings. 

On March 16, 1913, 24 rats were caught at 934 
(interior) Velasquez beneath a wood pile. Nest 
was made of coconut-shell fibre and pieces of cloth. 



108 PLAGUE 

On 'March 17, 1913, 14 rats were caught under 
a pile of hay and straw at 173 Velasquez. Nest was 
made from straw, chaff and hay. 

The following articles of food were found in 
the above-mentioned nests: chicken bones, rice, 
coconut, fish and bread. 

MEISIC DISTRICT 

At 822 Sacristia 6 dead rats found in holes. 

At 540 T. Alonso a family of 8 rats was smoked 
out and all were killed. 

At 514 same street 6 rats were smoked out and 
killed. 

At 538, interior, same street, 4 rats were smoked 
out and killed. 

At 546 same street 4 rats were smoked out and 
killed. 

At 715 San Bernardo dead rat found in a hole. 
Nest made of banana leaves and rags. 

At 627, interior, Zacateros, 9 rats were smoked 
out and killed. 

At 669 Benavides 6 rats were smoked out of 
four runs and were caught. 

At 631 Zacateros 2 rats were smoked out and 
killed. 



ITS CONTROL AND SUPPRESSION 109 

At 417, interior, Misericordia, 4 rats were se- 
cured in two holes under a tile floor. Many rats 
were caught at this number (interior) in traps. 

At 221 Espelita 7 rats were found in a nest 
made of palm leaves and excelsior; location of run 
way and nest beneath tile floor. 

At 124 Tetuan, in a nest of straw and lint, 5 rats 
were caught by hand, alive. 

At 415 T. Alonso one live rat and 3 dead ones 
were dug out from beneath a tile floor. 

SAMPOLOC DISTRICT 

At 1001 Bilibid Vie jo there were 5 rat runs, 
in a Chinese store. Eight rats were secured in a 
nest under the cement floor. Nest made of straw 
and paper. 

At 928 San Sebastian there were 8 rat runs. In 
one of them there were caught 8 rats. The nest 
was made of straw. 

At the same address, later, 3 rats were caught 
in another run and 8 young rats, with eyes still un- 
opened, were found in a nest of straw. A supply 
of bread was on hand in this nest. 

At 629 Tanduay 20 rats and nests of straw and 
paper were found. 



110 PLAGUE 

At the same address upon another day another 
rat run was found and one large rat and 16 small 
ones were taken from a nest made of rags, straw, 
and fibres. 

PACO DISTRICT 

At 1115 San Andres in a Chinese tienda (food 
store) , a long rat run and a nest of rags, straw, and 
paper, and 30 small rats were found. 

One nest in a bamboo tree 30 feet above ground 
was found. Rats had been observed going up the 
tree and one was caught at the foot of the tree in a 
trap. 

SAMPOLOC DISTRICT 

At 629 Tanduay 14 young rats and a nest of 
straw, paper and rags were found in a stable. 

Same address, later, one rat run and nest of 
straw and rags with one large rat and 16 small ones 
were found. 

TONDO DISTRICT 

March 27, 1913, one rat was caught alive inside 
of a bamboo timber in house at 51, interior, Pes- 
queria. 

At 631 Azcarraga 4 young rats were found in 
a nest of paper, leaves, and hay. Chicken bones, 
crab shells, and rice were present in the nest. 



ITS CONTROL AND SUPPRESSION 111 

A young python was caught in a lumber yard in 
the Santa Cruz District in June, 1913. In his 
stomach was found a half-grown rat. Another 
snake was caught in a rat trap at the same address 
about the same time. 

Plan for Household Rat Destruction. — 
The following plan for household rat destruction 
was proposed by me to the Director of Health. It 
is considered worthy of trial if rat plague appears 
in new districts. 

Proposal for periodic household rat poisoning in 
Manila. 

Proposed that, upon a certain day of each week, rat 
poison be issued free to all applicants (householders) in 
Manila who agree to place same about their premises, 
permitting the poison to remain in place for 48 hours. 

Instructions and poison placards to be issued with the 
poison. Issues to be made from Station Health Offices and 
records of issue to be kept. 

Collections of dead rats to be made at the end of £4 
hours and 48 hours by Bureau of Health employees. 
Poison portions to be collected and turned in at the 
Station Health Offices at the end of 48 hours, that is, at 
the time of the last rat collection. Rats to be tagged 
and examined for plague in the usual manner. 

Due newspaper notice of the plan and of the gratuitous 
issue of poison to be given to the people and their coopera- 
tion requested. 

Plan to be tested for at least two months. 



112 PLAGUE 

• MULTIPLE HOUSE INFECTION 
Memorandum concerning 1364 Calle Sande: 
Within 72 hours (April 25-27) five fatal cases 
of plague, all in Filipinos, occurred in Manila. The 
five deceased persons lived at 334 C. P. Rada 
(Meisic), 1419, interior, C. Dagupan, 1364 C. 
Sande (Tondo), 642 C. Ylala (Meisic), and 1492, 
interior, C. Dagupan (Tondo). 

The following relationships were established by 
inquiry and investigation and the circumstances 
point strongly to a common source of infection and 
to a single geographic focus of plague infection in 
connection with all of the cases, viz.: at 1364 C. 
Sande (Tondo). 

Jose Raymundo, boy, aged fifteen, lived at 334 C. P. 
Rada and worked daily until taken sick on Tuesday, 
April 22, at 1364 Sande, in the shop of Simplicio Enriques, 
a silversmith, who lived part of the time at the same 
address. 

Jose Raymundo died of bubonic plague at San Lazaro 
Hospital on Friday, April 25, 1913. 

Norberta Mendoza, woman, aged fifty-six, lived at 
1418, interior, C. Dagupan. She was the mother-in-law 
of Simplicio Enriques, the silversmith at 1364 Sande, and 
visited her son-in-law there frequently and within a few 
days of her last illness. She was taken sick April 22 and 
died at 1419, interior, C. Dagupan, on the morning of 



ITS CONTROL AND SUPPRESSION 113 

April 26. At autopsy at San Lazaro morgue, the same 
day, bubonic plague was found to be present and the 
cause of her death. 

Trinidad Galves, a young woman, aged sixteen, lived 
at 1364 Sande and was taken sick there on April 25. She 
was removed to San Lazaro Hospital and died there 
April 26, extensive plague lesions being found at autopsy. 

Pablo Banzon, man, aged twenty-six, living at 646 
C. Ylaya, was taken sick on Friday, April 25. He was 
removed to San Lazaro Hospital Saturday afternoon 
and died there Sunday evening, April 27. He was shown 
to have plague by bacteriologic examination made at the 
Bureau of Science. He worked at 1364 Sande as a silver- 
smith, with Jose Raymundo and was employed by 
Simplicio Enriques. 

Simplicio Enriques, aged twenty-seven, a silversmith, 
conducting his business at 1364 C. Sande and employing 
Jose Raymundo and Pablo Banzon, was taken sick about 
April 23. He moved to two different houses in the in- 
terval between the onset of his sickness and his transfer 
to San Lazaro Hospital on April 27, first to 1419 C. 
Dagupan, interior, where he remained until the death of 
his mother at this house ; then to 1492 Dagupan, interior, 
from which place he was transferred to San Lazaro Hos- 
pital, where he died with bubonic plague a few days later. 
Diagnosis was confirmed at autopsy. 

The two women were patients of Dr. Hernando 
of Calle Ylaya. He recognized the case of the elder 
woman as a probable case of plague, after death, 
and reported the matter to the Bureau of Health. 

The house at 1364 C. Sande is of the type in 

8 



114 PLAGUE 

which cases of rat plague and human plague have 
recently been found. In our operations to put the 
house in a safe condition we found one dead rat, 
mummified, in the basement. Unfortunately, the 
workmen who swept it out did not note the exact 
location at which it was found. The house is in the 
midst of the district where rat plague has raged 
since early in March, 1913. The basement con- 
tained unauthorized and illegal sleeping rooms until 
a few days before this outbreak when they were 
removed in the course of our antiplague operations. 
The building is constructed of bamboo with a nipa 
thatch roof. 

The front part of the basement was paved, but 
the pavement was undermined and broken. Being 
convinced that dead plague rats were present in 
the vicinity of this house and probably within it, I 
directed that the cement floor under the silversmith 
shop and the barber shop, located upon the ground 
floor at this address, be torn up. Accordingly, this 
was done (April 28) and three dead rats and one 
live one were found beneath the cement. As the 
bodies were mummified and unfit for bacteriologic 
examination they were burned. The living rat was 
examined at the Bureau of Science but was found 



ITS CONTROL AND SUPPRESSION 115 

to be healthy. The cement floor was broken and 
permitted fleas from the dead rats to enter the base- 
ment room of the house which was occupied by the 
silversmith shop. The rats doubtless died from 
plague and the hungry fleas in due time attacked 
the nearest persons at hand, the unfortunate occu- 
pants of the silversmith shop and the two women 
who frequented the room also. 

These facts account for the epidemic at 1364 
Sande very completely. 

The premises at 1364 Calle Sande were quaran- 
tined by the following order: 

Manila, April 27, 1913. 

The premises 1364 Sande are hereby declared in 
Quarantine for Bubonic Plague by order of the Director 
of Health. 

The inmates will be permitted to leave the building 
and find quarters elsewhere, provided they leave their ad- 
dresses with the policeman in charge, so that they may be 
readily found. They must remain in the District of Tondo. 
If they remain in the house they will be obliged to stay 
in the upper story of the house and will have to arrange 
for meals to be sent in. 

The barber shop and " platero " shop are hereby 
ordered closed until further orders. 

By order of the Director of Health. 

[Signed] T. W. Jackson, 

Medical Inspector, in Charge of Plague Suppression. 



116 PLAGUE 

Memorandum reporting circumstance surround- 
ing 2 cases of plague at 1226 C. Juan Luna (May 
17, 1913) : 

Valeriano Lausin, aged fourteen, Filipino male, 
Carmelo maker by trade but out of work at time he was 
taken sick, recently removed to this house from 917 C. 
Jaboneros where he had been employed. The patient 
fixes the date at about a week previous to his sickness, but 
the proprietors of 917 Jaboneros are positive in their 
statement that he left the place where he lived arid worked, 
at least two weeks before. This boy recovered. 

The circumstances and especially the occurrence 
of a second case at 1226 C. Juan Luna, indicate 
that infection was incurred here. 

Moreover, this house is in the midst of a rat- 
plague infected district. 

The house is of bamboo and nipa construction 
and contained illegal basement rooms until a week 
ago. About 60 persons lived in this house which 
was once licensed as a tenement but which is un- 
sanitary in a multitude of ways. Bamboo construc- 
tion, overcrowding, dirty condition and absence of 
proper drainage, water-closet, proper kitchens and 
paved ground floors, together with bad ventilation, 
made it a dangerous habitation and the added con- 



ITS CONTROL AND SUPPRESSION 117 

dition of plague infection made it necessary to 
vacate and quarantine the building. 

On May 15, at the daily inspection of contacts 
in the house 1226 C. Juan Luna, Filomena Sunga, 
aged nineteen, and a relative of the owner of the 
building, was found to be sick. Her only symptom 
was fever, but she was transferred to San Lazaro 
upon suspicion and promptly developed symptoms 
of plague. She died in a few days and the diagnosis 
of plague was verified at autopsy. The following 
order was issued : 

Station " C," Tondo, Bureau of Health, 

Manila, P. I., May 15, 1913. 
By order of the Director of Health, the house No. 1226 
C. Juan Luna is declared infected and is quarantined this 
date, for Bubonic Plague. The house will be vacated and 
a policeman will register the names of all residents and 
the addresses to which they remove. 

The residents may remove their personal effects but 
will not be permitted to return while the quarantine is in 

effect - [Signed] T. W. Jackson, 

Medical Inspector, Station "C," Tondo. 

Memorandum: Human body (dead from 
plague) and dead rats found in the same basement 
room. Upon March 21, 1913, a Filipino laborer 
living at 140 Calle Perla, Tondo, was found dead 
from bubonic plague. 



118 PLAGUE 

Upon careful investigation and search of the 
premises the following findings were disclosed: 

One rat, large, mummified and dry and there- 
fore dead for at least one week, was found clinging 
to a bamboo wall just back of the cot upon which the 
dead human body was found. 

In a section of bamboo, in a timber constituting 
the ceiling of the basement and also the upper part 
of the door frame, a rat, dead and dried up, was 
found. This section was the end section of the 
timber which was partly covered with nipa thatch, 
with which the sides of the house were covered. The 
ends of a number of the outside rafters (bamboo) 
were found to be gnawed through. 

Similar conditions were found in adjoining 
houses and in one case a live rat was driven out of 
a nest in the bamboo. 

Sample of Detailed Orders Issued. — Sample 
of detailed orders issued by Medical Inspector in 
Charge of Plague Suppression. Similar orders 
were issued whenever new districts were entered or 
new work undertaken. 

Memorandum Order. Effective March 25, 1913 : 
Beginning to-day, IS men under Assistant Inspector 
Par&s, will commence cleaning operations at C. Ostra, 




BAMBOO HOUSE SUPPORTS SEALED WITH CEMENT TO PREVENT ENTRANCE OF RATS 
(MANILA PLAGUE CAMPAIGN) 



ITS CONTROL AND SUPPRESSION 119 

extending from the Bay to C. Sande and will clean towards 
C. Moriones. They will be provided with a disinfecting 
pump and will disinfect the ground surfaces wherever 
disturbed, outdoors and indoors. Cleaning is to be done 
in the most thorough manner possible, searching mean- 
while for rat nests and rat harbors ; re-piling wood, tiles, 
stones and merchandise ; moving all movable goods out of 
doors in their search for rats and rat-holes or nests. All 
goods are to be piled above ground at an elevation of at 
least one foot. All bamboo beds and bamboo rafters and 
parts of the house (in the basements) made of bamboo or 
of double walls are to be thoroughly investigated for rats. 
All foodstuff attractive for rats is to be placed in covered 
boxes or galvanized iron cans, tin cans or barrels, with 
tight-fitting covers. Special attention is to be paid to 
straw, hay, shavings, grain, rat-holes, and food. 

Two men will be detailed to cement up ends of bamboo 
and rat-holes, but will not do general repairing. They 
will carry materials for mixing cement as needed and will 
not be wasteful of materials. 

If this force proves to be insufficient in numbers, addi- 
tional men may be detailed from the other working parties. 

[Signed] T. W. Jackson, 

Medical Inspector in Charge of Plague Suppression. 

Specimen order issued to Sanitary Inspector 
assisting in Plague Suppression by Medical In- 
spector in charge. 

Sanitary Inspector, Bureau of Health: 
Please place the gang of workmen under your charge 
in the square bounded by Calles Velasquez, Moriones, 



120 PLAGUE 

Concha and Manila Bay which is infected with rat plague. 
Treat the houses and properties there in the same manner 
in which other plague-infected districts have been treated, 
viz. : by policing the houses and yards, vacating all base- 
ments of light-material houses in which human habitations 
are illegally present; removing (with the consent of the 
occupants) all unauthorized basement sleeping places, 
beds, platforms, etc., and other illegal structures, closing 
up the open ends of bamboo rafters or timbers of the house 
with tin or cement. 

Where the occupants resist this action sanitary orders 
should be issued in the usual manner and interference 
should be stopped until the order is served and complied 
with. There are a number of most insanitary and unsuit- 
able shelters of bamboo, tin, etc., used for houses by a 
number of families in this square and it is desirable to 
tear down these huts if permission can be secured. If 
permission is refused orders should be issued on the usual 
form. 

[Signed] T. W. Jackson, 
In Charge of Plague Suppression. 

Specimen order issued by the Medical Inspector 
in charge of Plague Suppression. 

Station " C," Tondo, May 21, 1913. 

Redistribution of rat catchers and laborers engaged in 
antiplague work. Effective May 2, 1913. 

Sanitary Inspector Kennard and 20 rat catchers will 
move into Tondo District and trap and poison rats in the 
district bounded on the west by Manila Bay and on the 
east by Estero Reina. The work will be begun at the 
extreme north water boundary of this district and will 
proceed toward the south. 



ITS CONTROL AND SUPPRESSION HI 

Sanitary Inspector Brantigan with a similar number 
of rat catchers (20) will work within the same east and 
west boundaries and will begin trapping and poisoning at 
Calle Moriones, proceeding north. The poisoning and 
trapping is to be done in the most thorough manner pos- 
sible, as this is a dangerously infected district and rat- 
plague must be controlled and terminated here. 

The laborers, 60 men, divided into 4 parties of 15 men 
each under Assistant Sanitary Inspectors Jesus, De la 
Rosa, Laxamana and Paras, will continue the cleaning 
operations now under way on both sides of C. Juan Luna 
south of C. Moriones (plague localities in the same neigh- 
borhood), and thoroughly disinfect. 

One party of 15 men will work in the vicinity of C. 
Perla, vacate basements as habitations, search for dead 
rats in yards, houses, bamboos, under broken concrete, 
etc., and will close up openings in structural bamboo by 
means of tin and cement. Emphasis is placed upon the 
necessity for permanently vacating basements and men 
will be sent back over the ground daily to see that the 
persons moved out do not return. Reports are desired so 
that prosecutions for violations of the law may be insti- 
tuted if necessary. 

[Signed] T. W. Jackson, 

Medical Inspector in Charge of Plague Suppression, 

Specimen order issued to Assistants. 

May 4, 1913. Station "C," Bureau of Health: 
Please place work parties in (interior) 1 627-1629 
Sande and 525 C. Azcarraga, to clean, disinfect and thor- 
oughly investigate these premises and the houses, stables 
and other buildings in the vicinity. Search for rats, liv- 



m PLAGUE 

ing and -dead, rat nests and rats in bamboos and wood 
piles, stone piles, stables, under planks and elsewhere. 
Cement the openings in bamboos in houses or close with 
tin. Make notes on needed structural work. Do the work 
as thoroughly as possible. 

[Signed] T. W. Jackson, 
Medical Inspector in Charge of Plague Suppression. 

Method of Procedure in Collecting and 
Forwarding Rats Suspected of Plague Infec- 
tion to the Laboratory in Manila, P. L — Rat 
catching, — trapping and poisoning, — is conducted 
in accordance with instructions contained in the 
Sanitary Inspector's Handbook (pp. 36, 37, 38) 
issued by the Bureau of Health. 

Rats are collected in Manila and forwarded to 
the Bureau of Science for autopsy and for biologic 
examination for the presence of plague bacilli in 
the following manner: 

The various groups of rat catchers are provided 
with receptacles (iron pails) and a supply of a 
mixture of kerosene, cresol and water (kerosene 
10 parts, cresol 2 parts; water 88 parts). 

In these vessels, filled with the pulicidal mixture, 
the rats are immersed, with a minimum amount of 
handling, as soon as they are found (whether in 
traps or dead from poison). 



ITS CONTROL AND SUPPRESSION 123 

If captured alive they are killed and then 
promptly immersed. The mixture must be well 
shaken or stirred when used, as it separates upon 
standing. The immersion is, of course, for the pur- 
pose of destroying any fleas which may be present 
upon the captured rat. 

A paper tag showing the date and the exact 
location of the place of capture, with the name or 
group number of the rat catcher, is next affixed to a 
foot or to the tail of the rat and firmly tied upon 
the same, where it remains until the rat cadaver is 
finally disposed of. This tag is a card of strong 
Manila paper and the record upon it is made with 
an ordinary lead-pencil, as both ink and indelible 
pencil marks are apt to become illegible from wet- 
ting, whereas lead-pencil marks are little affected 
thereby. 

If desired, the disinfected tag in any given case 
of rat plague may be returned to the Bureau of 
Health, for identification, where an accurate record 
of every rat captured is kept. 

After dipping and tagging, the rats are taken 
to a central point, again dipped, and placed in large, 
tightly-covered, galvanized iron cans, in which con- 
tainers they are delivered to the laboratory by cart, 
once or twice daily. 



124 PLAGUE 

The Case of Mr. C. — The following are the 
facts concerning the case of Mr. W. C, a prominent 
American resident of Manila who suffered and died 
from plague in 1914. 

Mr. C, an editor, was taken ill with plague 
on the night of September 18, sought medical ad- 
vice and entered St. Paul's Hospital September 19, 
and was transferred to San Lazaro Hospital, Sep- 
tember 20, with an established clinical and bac- 
teriologic diagnosis of bubonic plague. He sur- 
vived till September 22. 

Upon September 21, in the course of disinfect- 
ing the business office of Mr. C, located in a district 
which had furnished a number of cases of both rat 
and human plague, a dead rat, mummified, was 
found in the right hand drawer of his desk and 
fleas were seen to hop from the drawer upon open- 
ing it. 

A flea killed by the disinfecting mixture at this 
desk was identified at the Bureau of Science as a 
rat flea {X enopsylla cheopis) . 

The rat cadaver was sent to the Bureau of 
Science and the following facts were reported from 
there some days later: 

The mummified rat and skeleton were pulver- 



ITS CONTROL AND SUPPRESSION 125 

ized in a sterile mortar and an emulsion was made 
and injected into guinea-pigs. The animals died 
from plague in a few days and plague bacilli were 
recovered from the tissues, as well as from the rat 
cadaver, by culture. 

A second rat cadaver, found at the same time 
in the same building, during cleaning operations, 
was similarly treated with identical results. 

There could scarcely be a stronger chain of con- 
vincing evidence against the rat and the flea, nor a 
more complete and convincing explanation of 
Mr. C.'s death than that afforded by these estab- 
lished facts and official documents. So far as I 
know there is no more striking case on record in 
the modern history of plague. 

Letter of Warning and Appeal. — The fol- 
lowing letter of warning and appeal for coopera- 
tion was suggested and framed by me February 10, 
1914, at the time that extensive rat plague was 
discovered in the heart of the business district of 
Manila. I presented it to the Director of Health 
with a strong recommendation for approval and 
publication and after consideration he approved 
and authorized publication upon February 10. No 
change was made in the wording of the proclama- 



126 PLAGUE 

tion, but it was issued over the signature of the 
Director of Health to give added force and au- 
thority to the appeal. The results were, as I had 
hoped they might be, highly beneficial. The tak- 
ing of the public into the confidence of the health 
authorities brought about a cooperation, without 
which our efforts in this difficult situation would 
have been sadly handicapped. It is my belief that 
this method should often be used by health author- 
ities, particularly where an intelligent community 
is threatened. 

To Whom It May Concern : 

You are hereby informed that the district bounded by 
Calles Rosario, Juan Luna, Dasmarifias and Plaza Cal- 
jderon (and possibly the neighborhood bordering upon this 
congested district) is a dangerous one for all persons liv- 
ing or conducting business therein, on account of the 
presence there of extensive rat plague. Six human cases 
(with five deaths) have recently developed there and many 
dead rats have been found. All human cases have been 
directly traced to rats dead from plague. 

The Bureau of Health is now doing everything within 
its power to make this district safe, but the attention of 
all citizens, property owners and tenants is called to the 
fact that they are required by law to keep their premises 
free from rats and to abolish all structural conditions of 
the buildings which favor the harboring of rats. This 
means rat-proofing, and owners are earnestly urged to 



ITS CONTROL AND SUPPRESSION 127 

perform this necessary work now, under the direction of 
the Bureau of Health. 

As a temporary expedient and safeguard all interiors, 
walls, floors and ceilings should be sprayed with kerosene 
daily, or at intervals of two days, to kill the fleas which 
carry plague from rats to human beings. All dark in- 
sanitary places used for living rooms should be vacated 
at once; all merchandise should be piled upon trusses at 
least a foot above the floor ; all straw, shavings and other 
material attractive to rats for nesting, should be removed 
and burned and all food materials upon which rats may 
feed and live should be placed in covered boxes, bins or cans. 

All rat-holes should be permanently closed and all 
broken cement or masonry should be repaired. 

Observance of these instructions may save the lives 
of yourselves, your families and your tenants. It is your 
duty to do your part in this matter, a part which neither 
the Bureau of Health nor the Government can do for you. 

Through very great effort the Bureau of Health has 
controlled plague in Manila and the Philippine Islands 
during the last two years. 

Residents must now do their part, and owners of 
property must permanently make their buildings safe for 
tenants, both for business and residential purposes. 

Bacteriologic Observations Made by Dr. 
Otto Schobl. — The following observations upon 
the bacteriologic aspect of the Manila; epidemic 
which we are considering were made by Dr. Otto 
Schobl of the Biological Laboratory of the Bureau 
of Science, Manila, and pertain to the cases of the 



128 PLAGUE 

first year of the epidemic. They were printed in 
the December number of the Philippine Journal of 
Science in 1913, but as they belong so definitely to 
the epidemic I am describing and as Dr. Schobl has 
expressed his willingness for me to quote them in 
full, I gladly accept his permission. Dr. Schobl 
advanced the possibilities of blood-culture diagno- 
sis to such a point of reliability that it became prac- 
tically possible for us to expect positive culture in 
nearly every case of true plague and the whole 
matter of bacteriologic diagnosis was perfected to 
a high degree of efficiency under his administra- 
tion of the laboratory work. 

He relates his observations as follows: 

During the recent outbreak of plague in Manila, I had 
the opportunity to make certain observations which are 
of interest. These observations were made in the exam- 
ination of: (1) Specimens taken from patients and from 
dead bodies at autopsies, (£) samples of blood-sucking 
insects collected in houses where plague patients had lived, 

(3) rodents caught by trap or poisoned in the parts of the 
city where plague cases occurred from time to time, and 

(4) domestic animals suspected of plague infection. 

I. Bacteeio logical Examination of Plague Patients 

In order to secure as early diagnosis as possible, the 
following procedure of investigation was adopted: 

1. The bubo was aspirated by means of a sterile hypo- 



ITS CONTROL AND SUPPRESSION 129 

dermic syringe. The material thus obtained was placed 
in the water of condensation of an agar-slant culture tube. 

2. At least 7 centimetres of blood were withdrawn 
from the cubital vein by means of another sterile syringe, 
and 5 centimetres of it were placed in an Erlenmeyer's 
flask, containing 200 centimetres of neutral meat broth. 
The rest of the blood was emptied into a sterile tube, and 
used for agglutination tests. 

Cultures obtained by this method were examined micro~ 
scopically, and the growths on various culture media were 
studied. Gram stain, Loffler's methylene blue, and hang- 
ing-drop method were used. Polar-staining and chain 
formation in liquid media and the characteristic type of 
colony on the surface of agar were looked for. Animal 
inoculation was performed in every case, and the culture 
isolated from each case was identified by agglutination 
test, rabbit's immune serum being used. 

The results of the bacteriological examination of a 
series of 24 patients are tabulated in the two following 
tables. Table I includes the fatal cases and Table II 
those cases which recovered. 

The diagnosis of plague could be safely made from the 
microscopical examination of the liquid aspirated from the 
bubo in the majority of the cases. However, in certain 
instances the amount of the aspirated fluid being small 
and the^bacilli very few, it was impossible to diagnose the 
case, especially when the cultures from the bubo were 
negative. Repeated examination of the patient was neces- 
sary under those conditions, but it happened in cases 22 
and 23 that the patients died of plague before a second 
examination could be made. The smears and cultures 
from case 22 remained sterile, while the smears and cul- 
9 



130 



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132 . PLAGUE 

tures made from the swelling on the neck of patient 23 
revealed the presence of pneumococci. Both patients died 
of plague, as was ascertained by examination of the organs 
after death. 

Two of the patients, cases 8 and 12, had numerous 
plague bacilli in the sputum at the time when the expec- 
toration showed the presence of blood (twenty-three and 
one-half and eighty- two hours, respectively, before death). 
In 3 cases I was able to prove the presence of Bacillus 
pestis in the skin lesions, intra vitam, fifteen, twenty-two, 
and forty-eight hours, respectively, before death. In case 
18 there was no doubt that the skin lesions, which cov- 
ered the whole body and the face, were of secondary 
nature, as the patient died shortly afterward. It was 
undoubtedly a case similar to those reported by Gotschlich 
and Zabolotny. 3 In the other two patients there was 
only 1 maculopapulous efflorescence on the foot in case 1 
(with a corresponding femoral bubo) and 2 lesions of the 
same type on the arm and forearm in case 4 (with a cor- 
responding axillary bubo). It is possible that these 
lesions were the original port of entry of infection. Num- 
erous plague bacilli were found in the skin lesions of these 
cases, both microscopically and in culture. 

The plague patients tabulated in Table II recovered. 
They were all treated with antiplague serum. While 
cases 5, 2, 19, and 24 appeared clinically to be rather 
severe, cases 2 and 20 were mild. 

It can be seen from the table that the plague bacilli 
may not be detected in the enlarged gland at first (case 2) 
and that their presence may be revealed only after re- 

3 Kolle und Wassermann : Handbuch der pathogenen 
Mikroorganismen. Gustav Fischer, Jena (1903) 2, 521. 



ITS CONTROL AND SUPPRESSION 133 

peated examination of the bubo. It is also evident from 
the results of repeated examinations that the plague bacilli 
disappear from the infected gland in a comparatively 
short time, as a rule at the time when pus starts to form. 
Contrary to the findings in patients who died, distinct 
phagocytosis was noticed in the smears made from the 
aspirated liquid in those patients who recovered and who 
had been treated with serum soon after the onset of the 
disease. It is undoubtedly this process that clears the 
gland of the infectious agents. 

The general opinion in regard to the presence of Bacil- 
lus pestis in the circulating blood seems to have been, as 
Thompson remarks, that " the bacillus is rarely to be 
found in the peripheral blood stream before the agonal 
stage." 4 

The Austrian Commission, using few drops of blood, 
found positive blood culture in 40 per cent; Calvert in 
Manila in 100 per cent when examined twenty-four hours 
before death; Choksy, Berestneff, and Mayr in 45 per 
cent; and Greig in 60 per cent. The Indian Commission 
examined 28 patients, and obtained positive blood cul- 
tures in 16 out of 23 fatal cases. Not a single positive 
blood culture was obtained from the patients who sur- 
vived. The time of blood examination in positive cases 
was three and one-half to seventy-five and one-half hours 
before death. The amount of blood used was 1 cubic 
centimetre. Only 6 out of the 30 samples, which gave 
positive blood culture, were found positive by microscopical 
examination of blood smears. The following conclusions 
are based on these observations in regard to the septicemic 
stage of bubonic plague: (1) "A severe septicaemia may 

4 Journ. Hyg., Cambridge (1906), 6, 558. 



134 PLAGUE 

be present at a comparatively early stage of the disease 
and for a considerable number of hours before death, and 
(2) the septicaemia may be of an irregular and fluctuating 
type." 5 

From the tables it will be seen that out of 15 patients 
examined by me, 14 gave positive blood culture; and of 
these 3 recovered. One blood culture revealed the pres- 
ence of streptococcus in addition to Bacillus pestis. The 
results of the examinations tabulated in Tables I and II 
show, in agreement with the findings of the Indian Com- 
mission, the occasional early occurrence of plague bacilli 
in the blood stream, as the time of examination in the 
positive cases varied from one hour to one hundred six 
hours before death. In consideration of the ephemeral 
character of the septicemic stage of plague, as evidenced 
by repeated blood cultures in the three patients who re- 
covered, one can hardly avoid the impression that there 
is a certain degree of septicaemia in every case of plague. 
The possibility of detecting the bacillus in the circulat- 
ing blood increases in proportion with the quantity of 
blood used for culture. The best chance to recover plague 
bacilli from the circulating blood seems to be in the stage 
of high fever and general prostration. 

The phenomenon of agglutination of plague bacilli by 
the serum of patients was first observed by Wissokowitsch 
and Zabolotny in 1897 6 and later confirmed by the Ger- 
man Plague Commission. Vagedes, Klein, and others 6 
pointed out the defects of the reaction as a diagnostic 

5 Ibid. (1907), 7, 395. 

8 Referred to in Kolle und Wassermann : Handbuch der 
pathogenen Mikroorganismen (1903), 2, 524. 



ITS CONTROL AND SUPPRESSION 135 

means. Aside from the technical difficulties, the reaction 
was found inconstant, and its occurrence was not noticed 
until the second week of the disease and even then only 
in low dilutions of the serum. 

Although the recent work of Strong 7 and of Strong 
and Teague 8 has reduced the technical difficulties, the 
fact remains that positive agglutination of plague bacilli 
by the patient's serum cannot be obtained in the first week 
of the disease, and, therefore, the isolation of plague 
bacilli from the body of the patient is still the only quick 
and safe method of plague diagnosis. 

Having utilized the technic devised by Teague, I have 
had no difficulty in performing the agglutination test in 
plague. The emulsion of plague bacilli, to be used for 
the test, was prepared by suspending young cultures of 
virulent plague bacilli, grown at 30° C, in salt solution 
and filtering the suspension through filter paper. No 
antiseptic was added nor heat applied. Serial dilutions 
of unheated patient's serum were mixed with equal amounts 
of bacterial suspension in small test tubes. Incubation 
at 35° C. followed. Controls, consisting of serial dilutions 
of normal human serum as well as bacterial suspensions 
without serum, excluded any possible error which might 
have been caused by spontaneous sedimentation of the 
bacterial suspension; while a parallel test with highly 
agglutinant serum facilitated the reading of positive 
results. 

Altogether, 22 tests were performed on 15 patients, 
11 of whom were fatal cases and 4 of whom recovered. 

7 The Philippine Journal of Science, Sec. B. (1907), 2, 
155. 

8 Ibid. (1912), 7, 194-201. 



136 PLAGUE 

In the negative reactions, the duration of the disease at 
the time of examination ranges from two to six days. 
The non-fatal cases showed slight agglutination from the 
sixth day on. From that day, the agglutination titer of the 
serum was found to rise, and the agglutinins persisted in 
the blood of convalescents up to the seventh week of the 
disease. 9 

It must be borne in mind that the patients, who showed 
positive agglutination, had been vigorously treated with 
antiplague serum. Nevertheless, in consideration of the 
low titer of the curative serum (dilution 1 : 32, agglutina- 
tion positive; dilution 1: 64, agglutination negative), the 
rise of the agglutinant power of the patient's serum in 
dilutions higher than 1 : 16 cannot be explained as wholly 
due to passive immunity, but rather to active immunity 
arrived at on the principle of simultaneous immunization. 

From the preceding observations the following con- 
clusions are drawn: 

1. The importance of blood cultures as a diagnostic 
means is evident from the fact that positive blood culture 
was obtained in practically every case that was examined 
in the febrile stage of the disease, even when buboes or 
signs of pulmonary involvement had not been detected 
clinically. 

2. It is also evident that Bacillus pestis may be found 
in the circulating blood of the patients even in cases which 
subsequently recover. 

3. The period of time during which Bacillus pestis 
circulates in the blood is evidently short and irregular. 

9 It is hoped that it will be possible to examine some of the 
survivors for agglutination from time to time. 



ITS CONTROL AND SUPPRESSION 137 

4. Mixed infection may be encountered in plague sep- 
ticaemia (Streptococcus, Pneumococcus) . 

5. The agglutination test is of no value for the diag- 
nosis of plague, as it was found positive only in con- 
valescents. 

6. Phagocytosis of plague bacilli in the bubo was 
noticed only in patients who recovered after being vigor- 
ously treated with curative serum. 

7. The presence of numerous plague bacilli in com- 
paratively insignificant skin lesions during the life of the 
patient points to the possibility of direct transmission, 
while the fact that a patient without any apparent bubo, 
who is not so sick as to be detained from his daily occupa- 
tion, may expectorate large numbers of plague bacilli, are 
facts of great importance with regard to the communica- 
tion of the disease. It is obvious that the last-mentioned 
condition might, and very likely does, give rise to an epi- 
demic of pneumonic plague if the atmospheric and sanitary 
conditions are favorable. 

II. Observations on the Transmission of Plague by 
Blood-sucking Insects 

Judging from the data which have been collected from 
the literature 10 on the transmission of plague (Table III), 
Simond seems to have been the first to call attention to 

10 Centralbl. f. Backt., 1 Abt. (1897), 22, 87, 437. Re- 
port of Indian Plague Commission (1898-99). Zeitschr. f. 
Hyg. u. Infectionskrankh. (1901), 36, 89. Kolle und Wasser- 
mann: Handbuch der pathogenen Mikroorganismen (1903), 2, 
538. Zeitschr. f. Hyg. u. Infectionskrankh. (1905), 51, 268. 
Journ. Hyg., Cambridge (1907-10), plague numbers. Ibid. 
(1908), 8, 162, 260. 



138 



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ITS CONTROL AND SUPPRESSION 139 

the important part which blood-sucking insects, particu- 
larly fleas, play in the transmission of plague. Although 
many investigators have been successful in demonstrating 
the presence of Bacillus pestis in the digestive system of 
blood-sucking insects, it was not until the experiments of 
Gauthier and Raybaud that the actual transmission of 
plague infection by fleas was convincingly proved. Ever 
since the exhaustive and conclusive experiments, which 
were carried out both under natural and artificial con- 
ditions by the British Plague Commission, and the work of 
Verbijtski, which antedates the British Commission, were 
presented, there has been no doubt that the transmission 
of plague by blood-sucking insects, particularly by the 
fleas, is one, although not the only, mode of spreading this 
disease. It is obvious, as Herzog correctly remarks, that 
the factors which are responsible for the spreading of 
plague must be considered individually in each epidemic 
and in various parts of the world as well. There is no 
doubt that the importance of any insect in the trans- 
mission of plague depends on its habits as well as on those 
of the host, be it either animal or man. 

During the recent outbreak of plague in Manila, sev- 
eral samples of bed-bugs from the beds of the plague pa- 
tients and dog fleas from a plagueinfected house were 
collected and examined, but with negative result. 

In spite of the fact that it adds nothing new to the 
question of whether or not plague can be transmitted by 
fleas, since the question has been conclusively answered 
by the work of the Indian Commission, nevertheless the 
following observations of a small outbreak of plague among 
animals, the spreading of which was due solely to fleas, are 
of interest. 

One wild rat was inoculated with strain Iloilo 3 of 



140 PLAGUE 

Bacillus pestis. The skin adjoining the root of the right 
ear was scarified, and a loopful of the culture was smeared 
on the scarified skin. The rat was found dead three days 
after the inoculation. 

The cage containing the dead rat was immersed in 
kreolin solution. At autopsy the cervical glands were 
found slightly swollen, somewhat reddened, but no haemor- 
rhagic oedema of the surrounding tissue was noticeable. 
There was slight necrosis at the place of inoculation, show- 
ing superficial, purulent discharge. Clear effusion in both 
pleural cavities and one hemorrhage in the pleura were 
found. The lungs were hyperaemic, but otherwise normal. 
The spleen was of somewhat darker color, but otherwise 
normal in size and appearance. The liver showed a slight 
degree of parenchymatous degeneration, the congestion 
making prominent the structure of the organ. The typ- 
ical, although not constant, changes of the organ, which 
are characteristic of natural plague infection in rats, were 
absent. The kidneys were without macroscopic change. 
The lymph glands, with exception of the cervical nodes, 
were normal. 

Examination of the rat's fur revealed ectoparasites 
on the neck, under the chin, and back of the ears; these 
at the time of the examination apparently were dead. 
About 6 common rat fleas were found and identified as 
Lwmopsylla clieopis Rothsch. The parasites were im- 
mersed in sterile salt solution for three hours. When re- 
moved in a dry test tube, they began to move about slug- 
gishty. The intestinal tract of these fleas contained blood. 

Five of the fleas were crushed by means of sterile 
forceps, and inserted in a pocket under the shaved skin 
of a guinea-pig. The animal died of plague within three 
days, showing considerable hemorrhagic oedema around 



ITS CONTROL AND SUPPRESSION 141 

the place of inoculation, typical bilateral inguinal buboes, 
and characteristic changes in the spleen. Smears and 
cultures made from the bubo and spleen were positive for 
Bacillus pest is. 

Another wild rat, which was in a separate cage in the 
same room where rat 1 had been kept, died twenty-four 
hours after rat 1. The two cages were at least 10 centi- 
metres apart. Rat 2 harbored fleas of the same species 
as were found on rat 1. 

Numerous severe bites were detected back of the ears 
and on the neck of the dead animal. The post-mortem 
findings were identical with those described in rat 1 ; that 
is, cervical buboes, pleural effusion, and slightly enlarged 
spleen. 

It is well to remark that both rats had been kept in the 
same room for about six months. Fleas had never been 
noticed on our guinea-pigs. During the time the rats had 
been kept in the plague house no irregular results were 
noticed in plague-inoculated animals. At the time the 
first rat was inoculated no other plague-infected animals 
were in the plague house, and since that time another build- 
ing has been used for plague-infected animals. 

Two days after the death of rat g three guinea-pigs, 
which were kept in separate cages in the same room, were 
found dead of plague (smears and cultures were both 
positive). Several fleas (Loemopsylla cheopis) were found 
on the necks of these animals. They were collected and 
inoculated in the same way as the fleas from the first rat. 
The experimental animal, which was inoculated with the 
fleas, was killed and found to be infected with plague. 
The findings were local reaction, inguinal buboes, and 
typical spleen. Smears and cultures were positive for 
Bacillus pestis. 



142 PLAGUE 

Although numerous healthy guinea-pigs were ex- 
amined in the same plague house, no fleas could be found 
at that time, only the 2 rats and the first 3 guinea-pigs 
are positively known to have harbored fleas, the latter 
after the death of the rats and not before. 

The gross lesions in these naturally infected guinea- 
pigs were somewhat unlike those found in guinea-pigs in- 
fected either by vaccination or by intraperitoneal or sub- 
cutaneous inoculation. All except one showed primary 
buboes on the neck with more or less extensive hemorrhagic 
cedema extending in some cases over the thorax. There 
was little pleural effusion present; the spleen always 
showed typical changes of necrotic foci varying in size 
and number. In one instance similar foci were found also 
in the liver, large enough to be visible macroscopically. 
This was in a case where like changes were found in the 
lungs. 

Only one of the guinea-pigs showed an exception, in 
that the primary buboes were located in the inguinal 
region, with pelvic and axillary glands secondarily in- 
volved. These are the findings usually met with in guinea- 
pigs artificially infected with plague by the vaccination 
method, if the lower part of the abdomen be chosen for 
inoculation. The reason for such a deviation from the 
findings in the rest of the guinea-pigs may lie in the fact 
that this animal was almost completely deprived of hair 
by a skin disease. 

It is of importance to mention the skin lesions which 
were found on the necks of the guinea-pigs, particularly 
under the chin. Besides small red spots which appeared 
to be fresh flea bites, small, elevated, and fairly deep in- 
filtrations partly covered with moist scab were found in 
the skin under the chin. Other animals showed changes 



ITS CONTROL AND SUPPRESSION 143 

usually found in the scarified skin of guinea-pigs after 
artificial inoculation with plague material. The base of 
each cutaneous efflorescence was hemorrhagic and cede- 
matous. 

A histological study of the tissues of these guinea-pigs 
known to be naturally infected by plague fleas showed the 
following changes : 

The Cervical Bubo. — The enlarged lymphatic gland 
was surrounded with a thickened capsule. Necrosis ex- 
isted in the subcapsular part of the gland, where it formed 
an almost continuous circular zone, leaving the central 
part less changed. Smaller irregular necrotic foci were 
scattered throughout the section. Polymorphonuclears in 
various stages of disintegration were found throughout the 
section. 

The Lungs. — Very few blood extravasations were pres- 
ent in the alveoli; otherwise normal. 

The Spleen. — The capsule was thin. There were sub- 
capsular hemorrhages. The Malpighian bodies were 
somewhat enlarged, but of normal structure. Throughout 
the parenchyma irregular multiple necrotic foci were 
found, leaving but little of spleen tissue intact. Numer- 
ous polymorphonuclears which were present showed vary- 
ing degrees of karyorrhexis. 

The Kidneys. — The outline of the cells was indefinite ; 
a few miliary hemorrhages existed in the cortical part of 
the organ. 

The Liver. — There was excessive congestion, fatty de- 
generation, and pigmentation of the cells. The capsule 
was slightly thickened. 

The Skin. — The epithelium was missing in one place 
in the section, and cellular infiltration extended from that 
place into the subepithelial layer of the surrounding skin. 



144 PLAGUE 

The same kind of infiltration reached deep into the skin, 
stripes of cellular infiltration penetrating into the tissue 
along the muscle fibres. There was no direct connection 
between the cellular infiltration and the follicles of the 
hair. 

It may be well to describe in detail the time of death 
from plague among these and the other animals in this out- 
break, as well as the time when the plague house was 
disinfected. 

The first animal (rat 1) having been inoculated on 
August 27, in the afternoon, died of plague within three 
days (August 30). The second animal (rat 2) died 
twenty-four hours later. Guinea-pigs 3, 4, and 5 (see 
plan) were found dead on the morning of September 2; 
that is, two days after the death of rat 2 and three days 
after the death of rat 1. 

The same day that the three guinea-pigs were found 
dead of plague, rooms I, III, IV, and VI were thoroughly 
disinfected. The floor, the ceiling, and the walls were 
sprayed with kerosene and lysol solution. The remaining 
animals in room VI were destroyed, and the cages disin- 
fected. No animals were kept in rooms I, III, and IV at 
that time. 

Three days after the death of animal 5, guinea-pigs 
6 and 7 were found dead of plague, while the next day 
guinea-pigs 8 and 9 died. No death occurred on Septem- 
ber 7, but the next two days each recorded two plague 
guinea-pigs (10, 11, 12, and 13). On September 11, the 
last guinea-pig died of plague in this outbreak. The 
whole building was then thoroughly disinfected. No 
plague-inoculated animals were kept in the rooms after 
the first sign of the epidemic. After September 11, no 
more cases of spontaneous plague infection were observed. 



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ITS CONTROL AND SUPPRESSION 145 

It will be noticed that the epidemic lasted eleven days 
after the first animal died and fourteen days after animal 1 
was inoculated. Altogether, 14« animals out of at least 
200 animals exposed died of plague. 

No death occurred among rabbits, although these 
animals were distributed among the guinea-pigs. In fact, 
2 rabbits were surrounded by plague guinea-pigs 8, 9, 
and 10, but did not contract plague. 

From the epidemiological standpoint it is interesting 
to know the dimensions and location of the cages in which 
the animals were kept. 

Aside from the £ rats which were confined in ordinary 
traps that stood on a table 80 centimetres high, the rest 
of the animals were kept in regular metal animal cages. 
The dimensions of the cages are: Fifty centimetres long, 
36 centimetres broad, and 30 centimetres high. The cage 
stands on four legs each 10 centimetres long; the centre 
of the bottom of the cage holds a drain opening 8 centi- 
metres above the floor. 

The majority of the cages in room II were located 
on the floor ; some on the second shelf of a wooden rack. 
This last-mentioned arrangement, judging from the con- 
struction of the wooden frame, allowed a continuous pas- 
sageway for the fleas to the second shelf of the racks. 
On the other hand, the deaths among the guinea-pigs in 
room V were restricted to the cages standing on the floor, 
the majority of cages in that room being placed on tables 
80 centimetres high. 

Only a theoretical explanation can be given of the short 
duration and sudden cessation of the outbreak. One can 
assume with great probability that the first partial dis- 
infection drove the fleas away from the primary source 
of infection, and that they traveled as far as possible. 
10 



146 PLAGUE 

They finally settled in those guinea-pig cages which had 
not been molested by the first disinfection. Having no 
new supply of plague blood (all of the plague-infected 
guinea-pigs having been removed, most of them before 
death), the fleas soon cleared themselves of plague bacilli. 
The peculiar feature of the outbreak, namely, the failure 
to find fleas on the animals in rooms II and V, finds its 
explanation in the observation of the Indian Commission 
who found that the fleas " died or disappeared very 
rapidly." 

The following conclusions can be drawn from these 
observations : 

1. The common rat flea (Lcemopsylla cheopis) pre- 
fers the rat to the guinea-pig. 

2. In the absence of rats it will attack guinea-pigs 
rather than rabbits. 

3. The fleas which have sucked blood from rats or 
guinea-pigs afflicted with plague septicaemia were found to 
harbor virulent plague bacilli inside of their bodies. 

4. The transmission of plague infection by direct or 
indirect contact being excluded in our case, the fact that 
fleas of the same species and harboring plague bacilli were 
found on the rat and on the guinea-pigs, the presence of 
flea bites on the rats and on the guinea-pigs with positive 
findings of skin lesions on that part of the body where the 
fleas and flea bites were located, together with the anatom- 
ical picture of the findings in the guinea-pigs, lead to but 
one explanation; namely, that the plague infection was 
transmitted by fleas. 

III. Observations on Animals Suspected of Plague 

Out of the several tens of thousands of rodents ex- 
amined during the antirat campaign, we have found only 



ITS CONTROL AND SUPPRESSION 147 

two plague rats which showed the typical picture of 
natural plague infection in rat; that is, cervical buboes 
with surrounding oedema, subcutaneous injection, pleural 
effusion, enlarged spleen, and such changes of the liver as 
are characteristic of natural plague infection in rats. 
Microscopically, large numbers of plague bacilli were 
found in these cases, and pure cultures of Bacillus pestis 
were recovered from the spleen. Histological examination 
of internal organs, particularly that of the liver, con- 
firmed the bacteriological findings. The remainder of the 
plague rats exhibited only two of the signs of plague 
infection, namely, bubo and oedema of the surrounding 
tissue, and eventually hemorrhages. 

Besides plague infection, a great number of rats 
showed purulent conditions from causes other than plague. 
Abscesses of the lungs were frequently met with, and cer- 
vical or axillary buboes are not uncommon in Manila rats. 
Various pyogenic bacteria were found in the pus of such 
abscesses. Of the less common was Bacillus pyocyaneus 
and the pneumobacillus of Friedlander. Chronic plague 
was excluded in these cases since the animal inoculation 
failed to produce plague infection. 

More than half of the rats examined harbored para- 
sites in their organs. Echinococcus teniceformis was 
found in the liver of practically every gray rat, while a 
small Ascaris and Tcenia dimmuta were not uncommon in 
the intestines. Two rats were found to have sarcosporidi- 
osis, 2.6 per cent, showed rat leprosy, and 7.4 per cent, 
trypanosomiasis. One tumor of the mammary gland and 
one tumor in the axillary region were encountered, while 
one tumor of the large curvature of the stomach proved 
to be a chronic inflammatory tumor due to parasites. One 
peritoneal tumor in a rat (Mus decumanus) gave the im- 



148 PLAGUE 

pression of a malignant tumor on account of the miliary 
dissemination of the peritoneum. It was found to consist 
of muscle and spindle-cell sarcomatous tissue. Ectopara- 
sites were very seldom noticed, on account of the method 
of collecting the rats. When present, they were mites 
and fleas. 

In the naturally infected plague rats the rigidity of 
the fresh cadaver was pronounced. The primary bubo 
was in every case cervical. Cervical glands were enlarged 
and hemorrhagic with slight oedema of the surrounding 
tissue. The subcutaneous injection extended over the 
neck and chest. The inguinal glands were small and pig- 
mented. The lungs were collapsed, and showed hemor- 
rhagic foci. The spleen was slightly enlarged, firm, and 
dark red. The liver was rather large, firm, pale red, 
with shade of yellow, which was caused by minute yellow- 
ish foci thickly scattered throughout the tissue and visible 
through the capsule. The kidneys were hyperaemic. The 
intestines were without change. The serous membranes 
were pale with no hemorrhages. 

Histological examination of the tissue of naturally 
infected plague rats showed the following changes: 

Liver. — The structure of the organ was well marked; 
the veins dilated, trabeculae slightly compressed, nuclei 
well stained, and few of the liver cells showed vacuoles. 
Small foci, most numerous under Glisson's capsule, were 
scattered throughout the organ; they varied in size, but 
were not larger than a miliary tubercle. The small ne- 
crotic foci were found to consist of few necrotic liver cells. 
The centre of the larger foci was formed by degenerated 
and necrotic liver tissue, surrounded by round-cell infil- 
tration. Polymorphonuclears were also found in the zone 
of cellular infiltration. There was a slight degree of 



ITS CONTROL AND SUPPRESSION 149 

hemorrhage in each focus. Epithelioid cells and large 
vesicular cells with several nuclei were to be found. The 
foci, mentioned above, were sharply demarcated from the 
surrounding liver tissue, which appeared to be intact. 

Spleen. — The structure was well preserved, the capsule 
thin. The Malpighian bodies were normal as to the ele- 
ments of which they consist. Cells with pycnotic nuclei 
were scattered throughout the organ, and vesicular cells 
with small, deeply stained, excentrically located nuclei 
were present. Polymorphonuclears were found in the 
tissue in considerable numbers. No localized necrotic foci 
could be found in sections through the spleen. 

Cervical Glands. — The blood-vessels were considerably 
distended. A few hemorrhages and polymorphonuclears 
were present. (Edema of the capsules and surrounding 
tissue existed. Part of the gland was necrotic. 

Lungs. — The blood-vessels were distended. The alveoli 
contained homogeneous masses and blood. There were 
numerous subpleural hemorrhages. The bronchi were col- 
lapsed, and contained mucus. 

Kidneys. — The cortical part showed subdued struct- 
ure; the epithelial cells had an indefinite outline and occa- 
sionally showed vacuolization. The medullar part was 
better preserved. There were miliary subcapsular hemor- 
rhages. A few small foci were scattered throughout both 
medullar and cortical parts. They consisted of round-cell 
infiltration. 

Natural Plague Infection in a Cat 

The experiments of the German Plague Commission 
proved that cats showed considerable resistance to plague 
infection as cutaneous and subcutaneous inoculations 
failed to infect them. According to the Austrian Com- 



150 v PLAGUE 

mission, cats develop submaxillary buboes if fed on plague 
material. They are said by Albrecht and Gohn n some- 
times to recover. Out of four cats fed on plague material 
two died of plague, one showing submaxillary, the other 
mesenterial buboes. Virulent plague bacilli were found 
in the discharge from the nose and also in the faeces of 
cats which apparently did not become infected after hav- 
ing been fed on plague material. 

One case of spontaneous plague infection of a cat was 
recorded by Thompson 12 in Sydney. 

W. Hunter, 13 in Hongkong made observations on cats 
suffering from plague infection. The author also under- 
took a few experiments, and arrived at the following 
conclusions : 

1. Cats suffer from plague. 

2. The disease may be acute or chronic. 

3. The type of the disease is septicasmic. 

4. The animals may occasionally play a part in the 
dissemination of plague. 

5. In plague-infected areas cats probably become in- 
fected through rats, which they devour as food. 

6. In plague-infected districts possible plague infec- 
tion in cats is of great importance from a domestic point 
of view. 

On November 27, 1912, a sick cat was brought to the 
laboratory for examination. It was reported that the 
animal was found in a warehouse in which dead rats had 

11 Uber die Beulenpest in Bombay im Jahre 1897 (1897), 
II B, II C. 

12 Report of an outbreak in Sydney, 1900. Referred to 
in Kolle and Wassermann (1903), 2, 510. 

"Lancet (1905), I, 1064. 



ITS CONTROL AND SUPPRESSION 151 

been found some time previously. The rats were not 
examined. In the morning of the 30th, the cat was found 
dead in the cage where it had been kept under observation. 
The following are the post-mortem findings : 

The animal was a fairly well-nourished female. 14 The 
subcutaneous tissue, pericardium, mediastinum, and mesen- 
terium contained considerable amounts of fat. 

The subcutaneous tissue of the neck showed oedema and 
small hemorrhages. The submaxillary tissues were swol- 
len on both sides. When the fasciae and superficial muscles 
of the neck were removed, enlarged glands were found on 
both sides. These were closely attached to the submaxil- 
lary salivary glands. The surrounding tissue was cedemat- 
ous, but no hemorrhages were noticed in the vicinity of 
the enlarged glands. Upon section the glands were found 
to be necrotic, and upon pressure a thin purulent liquid 
escaped. There were no hemorrhages within the glands. 
Several enlarged lymph-nodes, smaller in size, could be 
followed down the neck on the left side. The lymph-nodes 
in the axillae as well as in the groins and peribronchial 
nodes were normal. The mesenteric glands were slightly 
enlarged and reddened. 

The lungs were slightly collapsed. A clear, sanguin- 
eous, slightly coagulated effusion was observed in both 
pleural cavities. The tissue of the lungs showed con- 
siderable oedema and hypostasis. The bronchi and 
pharynx showed no changes, the mucous membrane being 
pale and thin. 

14 The cat was the mother of 4 kittens which were about 
3 weeks old at the time the cat was delivered for examination. 
They were kept under observation for several weeks, but 
showed no signs of plague infection. 



152 PLAGUE 

The heart was normal. 

The spleen was enlarged, of light red color, with fol- 
licles slightly prominent. 

The stomach contents was blackish in color ; there were 
no hemorrhages or ulcers in the mucosa. 

The liver was somewhat enlarged. The organ showed 
prominent structure, the centres of the acini being red, 
the periphery lighter in color. 

The kidneys were slightly enlarged and pale. The 
capsule peeled off easily, the venae stellatae were prominent, 
the surface smooth; there were no hemorrhages. The 
cortex was increased in breadth and was of' the same 
color as the surface; the pyramids were darker in color. 
The organ was of fragile consistence. 

Suprarenals were normal, as were also intestine and 
bladder. 

The histological findings were as follows : 

Bubo. — The capsule of the gland was oedematous. The 
whole gland as seen in cross section had undergone necro- 
sis, except a few foci which still showed cellular structure. 

Lungs. — The alveoli were filled with homogeneous 
masses, containing but few degenerated epithelial cells and 
leucocytes. The blood-vessels were dilated, particularly 
in the subpleural part of the organ. In some places capil- 
lary mycotic emboli with subsequent hemorrhage were 
encountered. The large blood-vessels and bronchi were 
normal. 

Salivary Glands. — Those glands attached to the pri- 
mary bubo showed the normal structure of a combined 
mucous and serous gland. 

Liver. — There was considerable congestion. The 
centres of the acini showed parenchymatous and fatty 
degeneration. The cells on the periphery of the acini 



ITS CONTROL AND SUPPRESSION 153 

exhibited typical fatty infiltration. The large blood-ves- 
sels and small ducts were without change. 

Kidney. — The cells of the kidney showed various de- 
grees of degeneration, ranging from parenchymatous to 
fatty infiltration. There were a few capillary hemor- 
rhages and hyaline casts present. 

Suprarenals. — These showed slight degeneration. 

Spleen. — This organ showed congestion, a few hemor- 
rhages, and bacterial emboli; otherwise normal. 

The bacteriological examination of the material from 
this cat gave the following results: 
1. Smears: 

a. From the buboes showed degenerated leucocytes, 

many lymphocytes, and numerous bacteria, 
some of which resembled Bacillus pestis in their 
polar staining. 

b. From the spleen showed numerous plague-like, 

polar-stained bacilli. Round involution forms 
were present. 
£. Cultures: 

a. From the buboes were badly contaminated with 

Bacillus coli and Bacillus pyocyaneus colonies. 

b. From the spleen : A few scattered colonies of Bacil- 

lus pyocyaneus developed on the surface of the 
agar. Between the large colonies a scanty 
growth of dewy appearance was noticed. Smears 
made from this growth revealed plague-like 
bacilli of the cultural type, showing a few club- 
shaped involution forms. Subcultures were 
made in order to secure pure culture. They 
showed a pure growth of Bacillus pestis as in- 
dicated by the morphology of bacilli and shape 
of the colonies. Agglutination with plague-im- 
mune serum was positive. 



154 PLAGUE 

3. Inoculation experiments {vaccination method): 

a. One guinea-pig was inoculated with the material 

from the left bubo, another one with material 
from the right bubo. They died of plague on 
the third and fifth days, respectively. 

b. One guinea-pig was inoculated with the material 

from the spleen. It died of plague on the third 
day. 

c. One guinea-pig was inoculated with material from 

the nostrils obtained by swab. The animal sur- 
vived, showing no indication of plague. 

d. One guinea-pig was inoculated with material from 

the rectum obtained by swab. It died of plague 
on the fifth day. 

Although plague infection among cats is apparently 
a rare occurrence, the fact that cats may contract the 
disease in spite of the high degree of resistance to plague 
infection has to be considered from the hygienic stand- 
point. 

To appreciate the important role which cats may play 
in the spreading of the disease one need only consider the 
close contact of these animals with rats on one side and 
human beings on the other. It is also a well-established 
fact that not only plague-infected cats, but also those 
which have devoured plague-infected material and re- 
mained apparently normal, may excrete plague bacilli 
which have retained their full virulence. 

Notes on Plague in Hong Kong by Dr. 
Roberg. — During the Hong Kong epidemic of 
plague which preceded and was coincident with that 



ITS CONTROL AND SUPPRESSION 155 

of Manila, I visited that city twice (December, 
1913, and July, 1914), but I did not closely in- 
vestigate the methods adopted and carried out by 
the authorities there, for the reason that the Manila 
plan was so much more productive of results, as 
shown by the apparent inability of the Hong Kong 
officials to gain control of the disease. However, 
I received from Dr. David Roberg, of the Oregon 
State Board of Health, a copy of a report made 
by him to the Secretary of his State Board of 
Health, following an investigation of the Hong 
Kong epidemic and the methods there followed. 
I have Dr. Roberg' s permission to use his report 
and it is herewith presented. It is dated Manila, 
April 16, 1914, and is as follows: 

I have the following notes to present on the epidemic 
of bubonic plague in Hongkong. 

On April 5th when I arrived in Hongkong the epi- 
demic was rapidly approaching its height. With its onset 
in January there were 47 cases, in February 42, and in 
March 223. During the week previous to April 5th, there 
were 91 cases; during the six days I was in Hongkong 
they averaged 15 a day. 

Judging from previous epidemics the present one will 
be exceptionally severe. The season for the occurrence of 
human plague is from the months of February to July. 



156 PLAGUE 

The onset is gradual ; in May it reaches its maximum and 
then declines. In the epidemic of 1912, for the city of 
Victoria the monthly rate showed the following, January 9, 
February 22, March 61, April 265, May 513, June 346, 
July 105, August 11, and September 1. Comparing these 
rates with those of the present year it will be seen that 
the number for March far exceeds that of two years 
previous. 

Illustrating the season for human plague, with its on- 
set, maximum and decline, are the monthly rates for the 
city of Kowloon during 1912, when the following cases 
occurred: February 2, March 12, April 52, May 246, 
June 152, July 39, August 8, and September 3. 

The season for human cases is determined by the con- 
dition of the rats. At the close of the season in July the 
rats die off from plague in great numbers as it is then the 
hottest time of the year. During the months from Sep- 
tember to February the rats increase in number and in 
susceptibility to the extent of being sufficient to again 
infect human beings. Moreover every other year shows a 
marked severity in the epidemics of human bubonic plague. 
This is explained by the fact that it requires two years' 
time for the rat population to become of sufficient great- 
ness and susceptibility to cause a severe human outbreak. 
This is shown by the yearly number of cases since the year 
1911. During the years 1911, 1912 and 1913 respec- 
tively, there were 253, 1847, and 408 cases. During the 
present year the monthly rate is exceeding that of the 
heavy year of 1912. 

The severe epidemic in 1912 was a result of the influx 
of 50,000 Chinese refugees into Hongkong during the 
revolution in 1911. The number of rats in the native 



ITS CONTROL AND SUPPRESSION 157 

district depends upon the available food supply, and as 
a result of this human overcrowding the amount of waste 
food so increased in the houses, yards and streets, that the 
over accumulation of garbage could not be kept pace with. 
This influx also brought in great numbers of susceptible 
rats. 

The number of rats killed off during the epidemic in 
1912 were so great that in 1913 they had not recovered 
sufficiently to cause a severe outbreak during that year, 
and as a result of the lightness of epidemic in 1913, they 
are so increased in number and susceptibility now that they 
are causing a very severe epidemic in human beings. 

Of rats in Hongkong they have the Mus decumanus 
or drain rat and the Mus rattus or house rat. It is note- 
worthy that the drain rat is found plague-infected 
throughout the year, while the house rat is found infected 
only during the period in which the human epidemics occur, 
namely from February to July. The number of infected 
rats a year run parallel to the number of monthly cases. 

The bulk of human infection is due to the spread of 
house rats. Man also becomes infected by the drain rat 
when the drains are flooded by rain storms and the rats 
are driven into the houses. 

What has made plague permanent in Hongkong is the 
overcrowding of the native districts. Besides there is a 
floating population entering and leaving the native quar- 
ters, numbering about 4000 a day. The native houses 
have been built with double floors and walls which harbor 
the rats. Where the construction is of wood it is pos- 
sible to remove the rat spaces. It has been found since 
the introduction of plague into Hongkong in 1894, that 
those districts containing the greatest number of soft 



158 PLAGUE 

brick houses with hollow walls, have shown the greatest 
incidence of plague. This can not be remedied as it would 
involve the destruction of buildings on too large a scale. 

The Work of the Sanitary Board 

The area under the control of the Board comprises 
the Island of Hongkong containing 32 square miles, with 
a sea frontage of 13 miles in length. Included also is the 
old city of Kowloon which is situated one mile and a third 
across the harbor and contains two and three-fourths 
square miles. The city of Victoria on the northern shore 
of the Island of Hongkong has a sea frontage of 5 miles, 
contains about ten thousand domestic buildings, of which 
about one thousand are non-Chinese. 

The population of Hongkong is difficult to estimate, 
as the floating population is so great. In the 1912 census 
there were 446,614 Chinese and 21,163 non-Chinese. 

The city of Victoria is divided into 10 Urban Health 
Districts and old Kowloon into 2. There is an inspector 
in charge of each. These districts are built over an area 
averaging from 31 to 140 acres. The houses in these dis- 
tricts average one thousand and the population from 8000 
to 33,000. There are four inspectors in charge of the 
scavenging work, one for the disinfection stations in Vic- 
toria and old Kowloon, one for the cemeteries and two 
for general duty. 

The measures emploj'ed by the Sanitary Board are 
summarized as follows: 

1. The exclusion of rats from all dwellings by means 
of concreted ground surfaces, the protection of all drain 



ITS CONTROL AND SUPPRESSION 159 

openings and ventilating openings by iron gratings, and 
the prohibition of ceilings and of hollow walls in new build- 
ings and in those existing buildings from which they have 
been removed by order. 

2. The collection and bacteriological examination of 
all dead rats. Facilities for the collection of rats in the 
quarters are provided in the shape of small covered bins 
attached to lamp posts, telephone posts, electric light 
poles, etc. These bins contain a carbolic acid disinfectant, 
and the inhabitants are invited to at once put into them 
all rats found or killed by them. There are 650 of these 
bins distributed throughout the city and its suburbs, and 
each of them is visited twice daily by rat collectors who 
take all rats found by theim to the City Bacteriologist. 
Each rat is at once labelled with the number of the bin 
from which it is taken, and if subsequently found to be 
plague infected, a special survey is immediately made of 
the block of houses in that vicinity. All rat-holes and 
rat runs are filled up with broken glass and cement, de- 
fective gratings and drains dealt with, and rat poison 
distributed free to the occupants. If several plague- 
infected rats are found in one locality, a special house-to- 
house survey and cleansing of that district is made. 

3. The destruction of rats by poison, traps and bird- 
lime boards; special efforts in this direction being made 
just before the onset of the regular plague season which 
is in the months of from March to July. 

4«. The encouraging of the community to keep cats. 

5. The systematic cleaning and washing out of all 
native dwellings at least once in three months with a flea- 
killing mixture made by emulsifying kerosene in water. 

6. An efficient daily scavenging of all streets and lanes 



160 PLAGUE 

and the daily removal of refuse from the houses, coupled 
with the provision of covered metal dust-bins, to reduce as 
far as possible the amount of food available for rats. 

7. The disinfection of plague-infected premises by 
stripping them and washing them out thoroughly with a 
kerosene emulsion. The bedding, clothing, carpets, rugs, 
etc., are conveyed in a huge covered basket to the disin- 
fecting plant and sterilized with superheated steam. No 
objection is made to the treatment of plague cases in 
native hospitals, and no restrictions are imposed in regard 
to the burial of those dead with plague except the pro- 
vision of a substantial coffin. 

8. Every effort is made by means of lectures, ad- 
dresses and explanations to induce the native population 
to participate in the above preventive measures. 

Upon my last visit to Hong Kong, in July last, 
plague was abating. The South China Morning 
Post of July 15, 1914, contained the following 
statement : 

Plague is gradually disappearing from Hongkong. 
Last week's return shows that there were 26 cases, of 
which 19 were fatal. All were Chinese. The total number 
of cases for the current year to date is 2093, with 1939 
deaths resulting. 

I regret that circumstances do not permit me 
to relate in detail the work done and the observa- 
tions made during the closing six months of the 
Manila epidemic. 



ITS CONTROL AND SUPPRESSION 161 

Up to the day of my departure from the Philip- 
pines, in July, 1914, 1 remained in charge of plague 
suppression, but the added duties of administra- 
tion at San Lazaro Hospital and the coincident 
occurrence of a cholera epidemic prevented me from 
keeping a detailed record in such form as to per- 
mit reproduction here. It will therefore) suffice 
to say that the first six months of 1914 witnessed 
the passing of the most threatening situation that 
has confronted the city of Manila in years. The 
record of plague rats found does not convey an 
accurate idea of the prevalence of rat plague by 
any means, for the simple reason that, when found, 
the rat cadavers were in such condition as to forbid 
bacteriologic examination; and inasmuch as the 
bacteriologic test of plague had been used exclu- 
sively in determining rat plague up to this time, it 
seemed desirable to adhere to the original method. 

In February we found in one of the districts, 
in which we undertook systematic work in conse- 
quence of a few cases of human plague, a very 
large number of dead rats, in and adjacent to 
houses which furnished human plague cases. In 

one building alone more than 150 rat cadavers were 
11 



162 PLAGUE 

found during our cleaning and rat-proofing opera- 
tions. It is this district concerning which the letter 
to the public (already quoted) was written. 

The methods followed in treating this new and 
dangerous focus of infection did not differ from 
those practised during the previous year, except 
in the matter of intensity. Forces of the cleaning 
and rat-catching gangs were increased and the ut- 
most thoroughness of treatment was insisted upon. 
The results fully justified our policy and demon- 
strated again how feasible it is to fight plague suc- 
cessfully if adequate authority be given. 

During the last year of the epidemic in Manila 
it became the rule for us to expect our plague 
workers to locate and find the identical rat cadaver 
from which the infected fleas bore the disease to 
the human victim, provided the spot upon the floor 
where the patient's sleeping mat had been placed 
was known. In the better class of houses the rat 
(sometimes more than one) was found dead be- 
neath the floor, behind some post casing, or in other 
space caused by double construction. Time and 
again I have directed the removal of some panel of 
woodwork, some post casing, or a board of the floor 



ITS CONTROL AND SUPPRESSION 163 

with the full expectation (seldom unrealized) of 
finding a dead rat or a rat nest. These experiences 
were positively uncanny at times. In the houses of 
the poorer class, usually of bamboo and thatch con- 
struction, the finding of the rat was less easy and 
more uncertain, although the nest was repeatedly 
found, and as related elsewhere the dead rat itself 
might be found in a hollow bamboo timber, or in 
the thatch construction of the wall. In a house on 
Calle Echague, from which a Filipino and his wife 
were removed, dead, within a few hours of each 
other, several dead rats were found in the floor 
(the only piece of double construction in the whole 
house) within four feet from the spot where the 
sleeping mats were placed. A rat hole led to the 
nest and through this hole the fleas from the dead 
rats found their way to the human victims sleeping 
on the floor above the encased nest. 

These instances could be multiplied many times, 
but there is no longer any special reason to do so, 
as the rat and the rat-flea are so completely in- 
criminated as to render these repetitions quite un- 
necessary, however interesting they may be to the 
plague worker. The danger of pursuing these in- 



164 PLAGUE 

vestigations, to the persons so engaged, must not 
be lost sight of, and exposure of such nests and rat 
cadavers should invariably be preceded by thor- 
ough spraying of the place, and particularly of 
the spot where tearing out of double construction 
is to be done. I know of no more dangerous em- 
ployment than this, both for laborer and bystander. 



CHAPTER IV 

ITS DIAGNOSIS AND TREATMENT 

It was not my original intention to include the 
subjects of diagnosis and treatment in this presen- 
tation, except in so far as I have already referred 
to them in the relation of my Manila experiences 
in the preceding pages. I have decided, however, 
to add a chapter upon Diagnosis and Treatment, 
for the sake of completeness. No attempt will be 
made to present these subjects in the orthodox way. 

Rather, my remarks will be confined to such 
matter as I believe to be thoroughly practical and 
relevant. 

In my opinion, the day has arrived when we 
may properly exclude from such handbooks as this 
one (intended for practical guidance), all such 
methods of diagnosis and treatment as have failed 
to meet the test of actual experience through a 
reasonable length of time. Twice in recent years, 1 
I have described the diagnosis and treatment of 

1 Tropical Medicine (1907) and Hare's Modern Treat- 
ment (1911), vol. 1. 

165 



166 PLAGUE 

plague, attempting in each case to present a reason- 
ably full account of the methods employed and 
advocated by authorities, for theoretic reasons and 
from the recorded personal experiences of medical 
men throughout the world. There comes a time, 
however, when wheat and chaff must be separated 
and when methods which have failed, in application, 
to justify preformed expectations must be rele- 
gated to the department of historical medicine. 

Judging from recent medical text books it is 
evident that medical writers are generally accept- 
ing this view as the proper one. At any rate, my 
experiences and those of my medical friends during 
the Manila epidemic of 1912-1914, have led me to 
discard as impracticable, unproven, disproven or 
unpromising, certain plans of treatment formerly 
deemed worthy of trial. I do not refer to these 
methods individually but will content myself, in- 
stead, with reciting briefly the methods which I 
believe, from personal experience and the collected 
experience of others, to be worthy of continuance 
and of further trial. 

Diagnosis, — The rapid diagnosis of plague is 
always of the utmost importance, both from the 
view-point of prognosis and treatment, in the in- 



ITS DIAGNOSIS AND TREATMENT 167 

dividual case, and from the community view-point 
of the recognition of the presence of a dangerous 
communicable disease, with the resultant obligation 
falling upon the health authorities. 

The Biologic Diagnosis. — Let us understand, 
first and finally, that but one diagnosis is absolutely 
and irrefutably dependable, viz. : the biologic diag- 
nosis. Herein I would include not only the recov- 
ery of the pest bacillus from the patient, but the 
recovery and identification of the organism from 
inoculated animals, infected from blood, tissues, 
secretions or cultivated plague bacilli derived from 
the human patient or cadaver. 

This entire process involves a lapse of time of 
several days, and, while it is indispensable in the 
earliest cases of an epidemic, and highly desirable 
for the proper study of all cases of plague, it is 
impracticable and unnecessary, in communities 
where plague is known to exist, to carry out more 
than the first steps of the biologic diagnosis, viz.: 
the recovery of B. pestis (morphologic identifica- 
tion) from the patient. 

Necessity for Trained Bacteriologist. — It 
is evident that the services of a trained bacteri- 
ologist are indispensable in the accurate diagnosis 



168 PLAGUE 

of plague, unless (as rarely is the case) the ob- 
server himself is both clinician and bacteriologist. 
Even in this case it is far better for two persons, 
clinician and bacteriologist, to work together. I 
will not discuss the technic of the procedures of 
biologic diagnosis, which is described by Dr. Schobl 
in the preceding pages. Except under circum- 
stances of necessity, the clinician should always 
turn this work over to the bacteriologist* 

Serum reactions, when present, occur too late 
to be of service in practical diagnosis. 

The necessary procedures of the biologic diag- 
nosis include blood-culture, smear examination 
(microscopic) of aspirated material from the 
cedematous tissues surrounding gland masses and 
from glands themselves; examination of sputum 
smears and of thick-blood smears. 

All should be practised but, according to our 
Manila experiences, smear examinations of as- 
pirated material and blood cultures are the most 
reliable methods, in the hands of a competent bac- 
teriologist. Attention is invited to the reports of 
Dr. Otto Schobl, already quoted. 

Bacteriologic Procedure. — Dr. Schobl was 
able to secure positive blood cultures, within 24 



ITS DIAGNOSIS AND TREATMENT 169 

hours, from all of a long series of cases of plague, 
both bubonic and septicemic. As much blood as 
it was possible to secure was aspirated from super- 
ficial veins and introduced into the culture media 
at the bedside, ten c.c. being secured whenever it 
was possible. 

The smear preparations for staining and cul- 
ture inoculations upon slants were also made at the 
bedside from aspirated matter obtained from 
cedematous periglandular tissues or from gland 
puncture, an aspirating syringe being used. The 
drop or two of fluid which can be expelled from 
the hollow needle is usually sufficient for smears 
and tube inoculations. 

Non-biologic Diagnosis. — I do not contend 
that other diagnostic means than biologic ones 
should not be used in plague. 

On the contrary, it will inevitably happen at 
times that resort must be had to methods of diag- 
nosis which are purely clinical. When this is the 
case, treatment, along lines to be detailed presently, 
should be instituted upon the establishment of a 
presumptive diagnosis. This presumptive diag- 
nosis may be reached after due consideration of 
physical signs and symptoms. A carefully taken 



170 PLAGUE 

history of the onset and course of the disease will 
be valuable but unfortunately such histories can 
rarely be secured. It is far safer to mistakenly 
pronounce a case " plague " and to institute ap- 
propriate treatment, than it is to hesitate in the 
absence of a perfect clinical picture and to permit 
the golden moment for treatment to pass. 

It must be remembered that septicaemic, bu- 
bonic and pneumonic plague are all manifestations 
of systemic infection with B. pestis; that they are 
all expressions of the same disease; that they call 
for the same treatment and that when the distinc- 
tive signs of bubo or pneumonia appear the disease 
is dangerously advanced. 

It should also be realized that every case is, 
almost from its onset, a septicemic case, either 
mildly or overwhelmingly so. Accordingly the 
treatment should invariably be the treatment of 
septicaemic plague. 

The attitude of the diagnostician should be one 
of suspicion and he should have the courage to 
carry out antiplague treatment, practically upon 
suspicion. In this way only can the mortality of 
plague be greatly reduced. It is true of plague, 
just as it is true of cholera, that many of the fatal 



ITS DIAGNOSIS AND TREATMENT 171 

cases develop and become hopeless before the dis- 
ease is suspected or diagnosticated. It is also true 
that many fatal cases of plague, in times of epi- 
demic, completely escape recognition during life, 
the diagnosis being made in the autopsy room. 

Therefore, I lay great stress upon the necessity 
for an attitude of suspicion on the part of prac- 
titioners, wherever even a single case of plague 
(human or rodent) is known to have occurred. 

When it becomes necessary to establish a pre- 
sumptive diagnosis, i.e., without resort to the micro- 
scope, the following symptoms and physical signs 
will be found to be most significant. 

Symptomatology. — Acuteness of onset; ra- 
pidity of fever development; rapidity of the devel- 
opment of mental dulness or cloudiness, impairment 
of speech, delirium, stupor or restlessness; early 
and extreme prostration (perhaps more pronounced 
than in any other acute disease) ; extreme tender- 
ness over involved gland masses, in the bubonic 
type of plague; cough, with considerable frothy 
sputum, soon becoming blood-discolored, in the 
pneumonic type of plague; and early cardiac 
asthenia in all clinical types of plague, septicemic, 
pneumonic and bubonic. 



172 PLAGUE 

The following diseases may be confounded with 
plague, if symptoms alone are considered: typhus 
{eocanthematicus) , influenza pneumonia, broncho- 
pneumonia, severe malaria, septicaemia, acute toxic 
typhoid, venereal bubo, mumps and tonsillitis. 

I call attention again to the fact that mild cases 
of plague, septicemic and bubonic, occur at times, 
clinical pictures in such cases being incomplete. 

The statement that the prognosis in all cases 
of septicemic plague is hopeless is not confirmed by 
my experience. 

It should also be remembered that primary 
pneumonic plague and secondary pneumonia devel- 
oping in the course of systemic plague are quite 
different in their significance and mortality, pri- 
mary pneumonic plague being well nigh invariably 
fatal. 

Pathologic Considerations. — -Only the stu- 
dent of plague pathology, who has seen a large 
number of complete autopsies, can understand how 
universal is the involvement of organs, glands and 
tissues in systemic plague and how widespread is 
the distribution of B. pestis throughout the body, 
and he will best understand how treatment, to be 



ITS DIAGNOSIS AND TREATMENT 173 

in the least effective, must be given in the very 
earliest hours of the disease. 

Plague is an exquisitely septicsemic disease and 
this fact must never be lost sight of by the thera- 
peutist, who must realize that from the earjiest 
moment of infection all plague is septicsemic plague. 

Treatment, Conditions and Prognosis. — 
Passing to the subject of treatment let us, first of 
all, admit that even under the most favorable and 
approved conditions of treatment the mortality is 
extremely high. On account of the delay which 
usually occurs in the recognition of plague, — a 
delay which in the natural order of things is and 
must be the rule rather than the exception, because 
of the rapidity of onset of the disease and the fact 
that it occurs much more frequently in the lower 
social classes than elsewhere, — no brilliant results 
are to be expected from any plan of treatment. 

The matter of plague treatment is far from 
being in the same satisfactory state as the matter 
of preventive control. I do feel, however, that 
biologic treatment from the earliest possible mo- 
ment, with serum, is of the greatest promise, how- 
ever discouraging the general prognosis may be 
in plague. 



174 PLAGUE 

Serum Treatment. — Recent writers agree 
that there is no treatment with curative value ex- 
cept that with antipest serum. To this belief I 
subscribe assent, as I find it entirely in accord with 
my experience and that of my colleagues in Manila 
during 1912-1914. 

Holding this view, I can see no reason for 
repeating here the details of purely symptomatic 
treatment. Symptomatic treatment has for its ob- 
ject the securing of comfort and of relief from suf- 
fering for the patient and is highly proper in its 
place, remembering always that it is not curative 
and that if employed alone it is worse than in- 
adequate. 

Symptomatic Treatment. — Opiates (mor- 
phine by needle) for pain, delirium and excitement; 
application of ice bags and cold or tepid sponge 
bathing for high temperature ; stimulants for heart 
weakness, are all indicated and are required in 
nearly every case of plague. 

As a rule surgery is not called for nor appro- 
priate, except in cases which develop secondary sur- 
gical conditions, which conditions we need not con- 
sider at this time. 

Statistical Studies in Mortality. — The sta- 



ITS DIAGNOSIS AND TREATMENT 175 

tistical study of plague mortality from the point of 
view of treatment is misleading and unsatisfactory 
for reasons already given in our discussion of treat- 
ment, viz.: failure to secure early recognition and 
early serum treatment, and the greater incidence of 
plague in the lower social classes. 

Few statistical compilations divide the cases 
studied into moribund and non-moribund, and in- 
deed such division, being a matter of judgment, 
largely involves the personal equation of the 
observer. 

The ease with which statistics may be moulded 
to support theories, or to break them down, all 
with perfect honesty of purpose, is proverbial. 

To me, the spectacle of a single case of plague, 
apparently ill unto death, recovering under the ad- 
ministration of antiplague serum, is more impres- 
sive than the contemplation of statistics ; and I have 
seen more than one such case respond to serum 
treatment and recover. 

So far as it goes, however, the study of statistics 
supports the view that treatment with antiplague 
serum is effective. 

I have not at hand the records of the last 



176 PLAGUE 

20 or more cases, but of the first 68 cases of plague 
in the recent Manila epidemic, 32 were either found 
dead or died upon the same day that they were 
found. 

If we exclude these cases from consideration 
there remain 36 cases. All of these patients re- 
ceived serum treatment and ten of them recovered. 

It is at once apparent that this percentage of 
recoveries (27 per cent, plus) is far more favorable 
than the actual percentage of recovery in the series 
in which cases found dead and moribund are con- 
sidered, the recovery percentage here being a little 
more than 14 per cent. It is also quite fair, it seems 
to me, to make this separation of cases, or even a 
more liberal one, if we are to consider the effects of 
serum treatment statistically. 

Dosage and Technique of Serum Adminis- 
tration. — The amount of antiplague serum to be 
given will vary somewhat with the age and weight 
of the patient and with the apparent severity of 
the case. 

In general terms it may be said that adults 
should be given from 300 c.c. to 500 c.c. of serui 
by injection, 100 c.c. being given every four hours. 



ITS ^DIAGNOSIS AND TREATMENT 177 

The injection may be either intramuscular or in- 
travenous. 

In view of the improvements in technic of in- 
travenous administrations and its comparative 
simplicity, and especially in view of the uncertain- 
ties and delays of absorption from the tissues, the 
intravenous route should be given the preference. 
The serum may be delivered intravenously from a 
large glass syringe, the introduction being very 
slowly made, or through a gravity apparatus, as in 
the administration of salvarsan. The serum should 
not be diluted. 

The use of antiplague serum for protective (im- 
munizing) purposes is also recommended — espe- 
cially when exposure to infection has occurred — in 
the same way in which diphtheria antitoxin is used. 
Its protective properties are conceded to be some- 
what superior to those of plague vaccines as the 
protection conferred is immediate, whereas plague 
vaccines do not protect until sometime after their 
administration. The dose is from 30 c.c. to 50 c.c. 

Prophylactic Serum and Anaphylaxis. — 
On one occasion in Manila in 1913, when some 
30 persons were given prophylactic doses of serum, 
intramuscularly, following a particularly danger- 

12 



178 PLAGUE 

ous exposure to fleas from rats dead from plague, 
there occurred a number of cases of " serum sick- 
ness" (anaphylaxis). These persons suffered 
from severe urticarial, arthralgic and nervous 
symptoms, lasting for several days and a few were 
obliged to enter a hospital. In one case the symp- 
toms did not entirely abate for a week. It has been 
stated that newly-prepared serum is particularly 
apt to produce serum sickness when used for im- 
munizing purposes. This form of protection is 
brief (1 to 2 weeks) and is best suited for use where 
there has been special exposure. 

Plague Vaccines. — HafFkine originally pro- 
posed prophylactic immunization, using killed broth 
cultures of B. pestis ( carbolized to % per cent. ) , giv- 
ing two injections at intervals of 10 days. Statis- 
tically it seems to be shown that this prophylactic 
immunization with dead bacteria reduces the in- 
cidence and mortality one-fourth or one-half (ap- 
proximately). Experimentally, also, it appears 
that antibodies (agglutinins) are produced by the 
vaccine (and modifications thereof). Instead of 
broth cultures, normal salt solution suspensions of 
killed pest bacilli are usually used in vaccines at 
present. 



ITS DIAGNOSIS AND TREATMENT 179 

Castellani 2 has prepared a combined cholera 
and plague vaccine for use in countries where both 
diseases coincidentally prevail. It is a mixed 
vaccine, so prepared that 1 c.c. of the emulsion con- 
tains 1000 millions of plague bacilli and 2000 
millions of cholera vibrios. The cultures are grown 
on agar, killed by phenol and suspended in normal 
salt solution. 

He finds (1) that inoculation of the vaccine in 
the lower animals induces a production of pro- 
tective substances for the plague bacillus and the 
cholera vibrio; (2) that the inoculation of human 
beings is harmless (producing less reaction than 
the Haffkine inoculation) ; (3) that a small amount 
of agglutinins, both for plague and cholera, appear 
in the blood of most inoculated persons (similar to 
amounts produced by HarTkine's vaccine), a rough 
index only of the amount of immunity produced. 

2 A. Castellani : Journal of Ceylon Branch of British 
Medical Association, June, 1914. 



INDEX 



Anaphylaxis, 177 
Appearance of plague in Porto 
Rico, 26 
New Orleans, 26 
Manila, 26 
Appeal for public cooperation, 

126, 127 
Australia, plague in, 22 
Alaska, plague in, 22 
Africa, South, plague in, 22 
Africa, Central, plague in, 22 
Africa, East, plague in, 22 
Africa, British East, plague in, 

25 
Africa, Portuguese East, plague 

in, 26 
Asian marmot, 28 
Australia, rat fleas of, 32 
Activity of fleas, 33 
Attenuation of virulence of 
cholera organism, 35 
Bacillus pestis, 35 
Adaptability of rat to tempera- 
ture and environment, 51 
Anti-plague campaign in Manila, 

1912-1914, 57 
Amoy, importation of plague 

from, 59 
Anti-rat measures in R. R. cars, 

92 
Activity of fleas, 98 
Austrian Plague Commission, 133 
Agglutination of plague bacilli, 

134-135 



Animals suspected of plague, ob- 
servations on, 146-149 

Abatement of plague in Hong 
Kong in 1914, 160 

Anti-plague work, dangers of, 
163, 164 

Bacteriologic observations, 127 
Bacillus pestis, in air, 38 
in ants, 138 
in bedbugs, 33, 138 
conveyance by fleas, 28, 

30, 31 
cultivation of, 133, 138 
cultural characteristics 

of, 133, 138 
in circulating blood, 133, 

136 
in cats, 150 
effect of temperature 

upon, 34 
in flies, 33, 138 
in fleas, 138 
in lice, 33, 138 
effect of seasonal con- 
ditions on, 34 
in cockroaches, 33 
in sputum, 132 
stability of virulence of, 

35, 36 
in skin, 132 
Blue, Dr. Rupert, 31 
Brazil, plague in, 22 
Black Death of Europe, 20 
British East Africa, plague in, 25 
181 






182 



INDEX 



Bite of flea, 31 

Brazil, rat fleas of, 32 

Bedbug, conveyance of B. pestis 

by, 33 
Barber, Dr. M., 38 
Bacterial viruses for rat destruc- 
tion, 43 
Bacterial virus, Danysz, 53 
Bacillus, Danysz, 53 

use of, in Odessa, 53 
use of, in Cape Town, 53 
B. typhi murium, 53 
Bacillus, mouse-typhoid, of Loef- 

fler, 53 
B. enteritidis, Gartner's, 54 
Bacterial rat poisons, use of, in 

Japan, 54 
Beginning of Manila epidemic, 

60 
Binondo, Manila, plague in, 63 
Bamboo timbers, closing ends of, 

71 
Basements, insanitary, 72 
Birth-rate of rats, 73 
Bionomics of fleas, 77 
Batavia, Dutch India (Java), 77 
Bureau of Science, Manila, 92 
Barn rat, 99 

Burrowing ability of rats, 102 
Breaking up rat nests, Manila, 

106 
Bacteriologic examination of 

plague patients, 128 
Blood-sucking insects, transmis- 
sion of plague by, 137 
Bacillus pestis, insects found to 

contain (Table III), 138, 139 

Biologic diagnosis of plague, 167 

procedure, diagnosis, 168 



Cause of plague, 28 

Conveyance of plague, 28 

Control of plague, 40 

Crowell, Dr. B. C, 14 

China, plague in, 21, 22, 24 

California, plague in, 22 

Central Africa, plague in, 22 

California ground squirrel, 28 

Contact, plague through, 29 

Contagious plague, 29 

Contagion, India Plague Com- 
mission on, 33 

Cockroaches in plague convey- 
ance, 29, 33 

Cats, plague in, 29, 76, 149 

Chronic plague in rats, 35 

Chronic rat plague, India Plague 
Commission on, 35 

Currie, Dr. D. H., 31 

Creel, Dr. R. H., U. S. P. H. 
Service, 31, 101 

Castellani, Dr. Aldo (dedication), 
179 

Ceratophyllus fasciatus, 32 

Cat fleas, 3-2 

Ctenocephalus, 32 

Citellus beecheyi, 28 

Cholera epidemics, spontaneous 
abatement of, 35 
organism, attenuation of viru- 
lence of, 35 

California, a plague centre, 41 

Cost of rat proofing, 49 

Chemical poisoning of rats and 
ground squirrels, 54 

Community, summary of prevent 
tion for, 56 

Close of year 1912 in Manila, 67 



INDEX 



183 



Closing ends of bamboo timbers, 

71 
Cat plague case in Manila, 76, 149 

fleas, 78 
Correspondence of Philippine and 

Japan conditions, 83 
Comparative statistics in rat 

catching methods, 89 
Cresols, 94 
Coloration of rats, 99 
Conformation of skulls in rats, 

101 
Climbing ability of rats, 102 
Collection and forwarding of rats 

(Manila), 122, 123 
Case of Mr. C. (Manila), 124, 

125 
Concealing plague cases, 94 
Conclusions concerning blood 
culture in plague diagnosis, 
136 
from observations of plague 
outbreak among experi- 
mental animals (Manila) , 
146 
Cat, natural plague infection in, 

149-154 
Conditions, treatment and prog- 
nosis, 173 
Combined vaccines, 179 

Diagnosis of plague, 165 
Definition of plague, 28 
Digestive tract, infection through, 

29 
Dog fleas, 32 
Droplet infection, 38 
Destruction of rats by diseases, 

53 



Danysz bacterial virus, 53 
bacillus, 53 

use of, in Odessa, 53 
use of, in Cape Town, 53 

Destruction of rats by domestic 
animals, 54 

Disinfection of ship cargoes, 56 

Dead, proper disposal of, 56 

Dispersion of fleas from rat 
cadavers, Manila, 65 

Death-rate of rats, 73 

Dutch India, Batavia (Java), 77 

Duration of life of fasting fleas, 
79 

Dead rats in bamboo house tim- 
bers, 87 

Disinfection, theatre, Manila, 93 

Deception and concealment of 
plague cases, 94 

Differential points in rats, unre- 
liability of, 101 

Driving out rats with formalde- 
hyde gas (Manila), 106 

Dangers of anti-plague work, 163, 
164 

Diagnosis, rapid, of plague, im- 
portance of, 166 
biologic, of plague, 167 
non-biologic, 169, 170 

Dosage and technique of serum 
administration, 176, 177 

Extension of plague, 19, 22 
E gypt> plague in, 20, 22, 25 
East Africa, plague in, 22 
Epidemics, effect of seasonal con- 
ditions on, 34 
wane of, 35 
Epidemic pneumonic plague, 38 



184 



INDEX 



Economic importance of rat de- 
struction, 42 
Estimations of loss by U. S. Agri- 
cultural Department, 42 
Effect of superstitions and re- 
ligious beliefs in India, 43 
of rat poisoning and trap- 
ping, 73 
Epidemiologic facts concerning 

plague in Java, 82 
Examination of fatal cases of 
plague (Table I), 130 
of cases of plague who re- 
covered (Table II), 131 
Experimental animals, plague in, 
139-145 

Flea conveyance of B. pestis, 30 
Flies, conveyance of B. pestis by, 

33 
Fowls, plague conveyance by, 29 
Flea's stomach, capacity of, 31 
bite and plague conveyance, 
31 
Flea prevalence, effect of seasonal 

conditions on, 34 
Fox, Dr. Carrol, 31, 70 
Fleas, dog, 32 
cat, 32 
mice, 32 

ground squirrel, 32 
activity of, 33, 98 
Fumigation of ships, 46 
Flea carriers, objection to do- 
mestic cats and dogs as, 55 
Favorable conditions for spread 

of plague in Manila, 61 
First Manila cases in 1912, 62 



Fleas and their habits, 77 
bionomics of, 77 
rat, of Philippines, 78 
of Australia, 78 
of Italy, 78 
cat, 78 

per rat, variations in num- 
ber of (Java), 78 
Flea larvae, effect of temperature 
and humidity on, 79 
imago, effect of temperature 
and humidity on, 79 
Fasting fleas, duration of life of, 

79 
Flea prevalence, prediction of 
plague extension from, 80 
natural enemies of, 97 
activity of, 33, 98 
Field rat, 99 
Family Muridae, 99 
Ferocity of Mus decumanus, 102 
Feasibility of fighting plague suc- 
cessfully, 162 
of Manila policy of plague 
control, 162 

Great plague of London, 21 
Great Britain, plague in, 22 
Ground squirrel, California, 28 
Great Britain, rat fleas of, 32 
Ground squirrel, fleas of, 32 
Gartner's B. enteritidis, 54 
Geographic grouping of plague 

cases in Manila, 63 
Ground-floor sleeping quarters, 72 
General cleaning campaign, 

Manila, 88 
Garbage cans, sanitary orders, 

Manila, 93 



INDEX 



185 



Guinea-pigs as indicators of in- 
fected houses, 96 
Genus Mus, 99 
Gray rat, 99 
Gunomys (Nesokia), 100 
Gnawing ability of rats, 102 
German Plague Commission, 149 

History of plague, 19 
Hawaii, plague in, 22 
Hong Kong, plague in, 24, 58, 154 
Heiser, Dr. V. C, 31, 58, 70, T5, 

89 
Hobdy, Dr. W. C, 31 
House cats as rat catchers, 55 
Half wild cats as rat catchers, 55 
Human plague in Tondo district, 

Manila, 68 
Houses in Tondo, light material, 

71 
House disinfection by spraying, 

94 
Household rat destruction, plan 

for, 111 

Hong Kong, notes on plague in, 

by Dr. Roberg, 153, 154, 

155, 156, 157, 158, 159, 160 

the work of the Sanitary 

Board, 158 
abatement of plague in 1914, 
160 
Haffkine vaccine, 178, 179 

Introduction, 11 
India, plague in, 24 
Indo-China, plague in, 24 
Infection through digestive tract, 

29 
Ingestion, plague, 29 
India, rat fleas of, 39 



Italy, rat fleas of, 32 
India Plague Commission on con- 
tagion, 33 
o n chronic rat 
plague, 35 
Immunity, plague, 36 
India, effect of superstitions and 

religious belief in, 43 
Isolation of sick, 56 
Importation of plague from 

Amoy, 59 
Iloilo, P. I., plague in, 70 
Insanitary basements, 72 
Interpretation of the rat catch 

and plague incidence, 91 
Infected houses, guinea-pigs as 

indicators of, 96 
India Plague Commission, 100 
Insects found to contain Bacillus 

pestis (Table III), 138, 139 
Importance of rapid diagnosis of 

plague, 166 

Japanese anti-plague serum, 18 
Japan, plague in, 22, 25 
Java, plague in, 25 
Japan, bacterial rat poisons, use 

of, in, 54 
Jackson, Dr. T. W., correspond- 
ence, 75 
Java, Batavia, Dutch India, 77 
Xenopsylla cheopis in, 77 
variations in. number of fleas 

per rat, 78 
epidemiologic facts concern- 
ing plague in, 82 
Javan village house, 84 

"bale bale," rats in, 86 
Java, sawah rat of, 100 



186 



INDEX 



Jumping ability of rats, 102 
Java, studies of rat cadavers in, 
104 ' 

Kerr, Dr. J. W., 31 
Korn, Dr. W., U. S. P. H. Ser- 
vice, 87 
Kerosene as an insecticide, 94 

London, great plague of, 21 

Lantz, Dr. D. E., 31 

classification of rats, 99 

Lcemopsylla cheopis, 32 

Louse, conveyance of B. pestis 
by, 33 

Loeffler, mouse-typhoid bacillus 
of, 53 

Laboratory-proven plague rats 
and others in Manila, 61 

Light material houses in Tondo, 
71 
Manila, 85 

Letter of warning and appeal, 
125, 126 

Location of rat cadavers in re- 
lation to human plague cases, 
Manila, 162, 163 

Mortality, 22, 23, 174, 175 
Menace of plague, 28 
Manila, plague in, 26 
Manufacture of anti-plague 

serum, 18 
Middle Ages, plague in, 20 
Mexico, plague in, Q2 
Mauritius, plague in, 22, 25 
Mediterranean ports, plague in, 

22 
Marmot, Asian, 28 



Mice, fleas of, 32 

Manchuria, pneumonic plague in, 

37 
Methods of entry of rats into 

ships and cars, 52 
Mouse-typhoid bacillus of Loef- 
fler, 53 
Murium, B. typhi, 53 
Manila, Anti-plague Campaign in 
1912-1914 in, 57 
epidemic, 1912-1914, 57 
plague at quarantine in, 58 
importation of plague from 
Hong Kong in 1912, 58 
Mariveles Quarantine Station, 59 
Manila epidemic, beginning of, 60 
Mortality and numbers of Manila 

plague cases, 61 
Manila cases in 1912, first, 62 
geographic grouping o f 

plague cases in, 63 
R. R. station focus, 64 
dispersion of fleas from rat 

cadavers, 65 
close of year 1912 in, 67 
Malolos, P. I., plague in, 69 
Manila, taking charge of plague 
suppression measures in, 70 
plague fighting organization 

in, 71 
rat plague in U. S. Army 
Commissary warehouse, 76 
habitations and plague, 83 
light material house, 85 
general cleaning campaign, 

88 
theatre, disinfection in, 93 
Mus rattus, 99 

alexandrinus, 99 



INDEX 



187 



Mus decumanus, 99 

ferocity of, 102 
Manila, breaking up of rat nests, 
106 
driving out rats by formalde- 
hyde gas, 106 
rat killing with dogs, 107 
rat nests in trees, 110 
snakes in rat traps, 111 
rat swallowed by snake, 111 
Multiple house infection (Ma- 
nila), 112-117 
Manila, collection and forwarding 

of rats, 122, 123 
Mr. C, case of Manila, 124, 125 
Manila, bacteriologic observation, 
127 
outbreak of plague among 
experimental animals, 139- 
145 
conclusions from observation 
of plague outbreak among 
experimental animals, 146 
San Lazaro Hospital, 13, 69, 

161 
location of rat cadavers in 
relation to human plague 
cases, 162, 163 
Mortality, statistical studies in, 

22, 174, 175, 176 
McCoy, Dr. C. W., 31 

New Orleans, plague in, 26 
Natural enemies of the rat, 43 
National aid, necessity of, 56 
Numbers and mortality of Manila 

plague cases, 61 
Nest materials, 86 
Natural enemies of the flea, 97 



Norway rat, 99 
Notes on rat runs, 105 
nests, 105 
food, 105 
Natural plague infection in a 

cat, 149-154 
Notes on plague in Hong Kong 

by Dr. Roberg, 153-160 
Non-biologic diagnosis, 169, 170 

Objection to domestic cat's and 
dogs as flea carriers, 55 

Order Rodentia, 99 

Outbreak of plague among ex- 
perimental animals (Manila), 
139-145 

Observations of animals sus- 
pected of plague, 146-149 

Plague conveyance, 28 
in 1910, 24 

conveyance by suction of in- 
sects, 33 

Porto Rico, plague appears in, 
26 

Public cooperation in plague con- 
trol, 126, 127 

Practicability of plague control, 
15 

Philippines, plague in, 22 

Peru, plague in, 22 

Persia, plague in, 25 

Portuguese East Africa, plague 
in, 26 

Public Health Service, U. S., 26, 
37 

Pulex irritans, 32 
pallidus, 32 

Plague pneumonia, secondary, 39 



188 



INDEX 



Pneumonic plague epidemic, 38 
Prevention problem, summary of, 

37 ' 
Pneumonic plague, 37 

in Manchuria, 37 
Plague immunity, 36 

treatment and diagnosis of, 

165 
control, 40 
prevention, 40 
suppression, 40 
campaign in San Francisco, 
41 
Poisons used for rat destruction, 

43, 44 
Poisonous gases, rat destruction 

by, 45 
Prevention for community, sum- 
mary of, 56 
Proper disposal of dead, 56 
Philippine Journal of Science, 

58, 70, 128 
Plague at quarantine in Manila, 
58 
from Hong Kong, Manila, 
! importation of, in 1912, 

58 
from Amoy, importation of, 

59 
cases, numbers and mortality 

of Manila, 61 
rats, laboratory-proven, and 

others in Manila, 61 
in Quiapo, Manila, 63 
in Binondo, Manila, 63 
cases in Manila, geographic 

grouping of, 63 
in Malolos, P. I., 69 
in Iloilo, P. I, 70 



Plague suppressive measures, Ma- 
nila, taking charge of, 70 
fighting organization in Ma- 
nila, 71 
Population, removal of, in emer- 
gency, 74 
Plague, cat, case of, Manila, 29, 
76, 150 
rat, in U. S. Army Commis- 
sary warehouse, Manila, 76 
Prediction of plague extension 

from flea prevalence, 80 
Plague prevalence, seasonal ex- 
planation of, 81 
in Java, epidemiologic facts 

concerning, 82 
Manila habitations and, 83 
Tondo (Manila) habitations 

and, 83 
cases, deception and conceal- 
ment of, 94 
commission, India, 100 
Postmortem changes, in rats 
(Table), 105 
in rats (illustration), 

105 
time of death of rats as 
indicated by, 104 
Plan for household rat destruc- 
tion, 111 
Plague patients, bacteriologic ex- 
amination of, 128 
examination of fatal cases of 
(Table I), 130 
of cases who recovered 
from (Table II), 131 
commission, Austrian, 133 
bacilli from circulating 
blood, recovering, 134 



INDEX 



189 



Plague bacilli, agglutination of, 
134, 135 

diagnosis, conclusions con- 
cerning blood culture in, 
136 

by blood sucking insects, 
transmission of, 137 

among experimental animals, 
outbreak of (Manila), 139- 
145 

outbreak among experimental 
animals, conclusions from 
observations of (Manila), 
146 

observations on animals sus- 
pected of, 146-149 

commission, German, 149 

in Hong Kong, notes on, by 
Dr. Roberg, 153-160 

in Hong Kong in 1914, abate- 
ment of, i60 

feasibility of fighting suc- 
cessfully, 162 

control, feasibility of Manila 
policy of, 162 

cases (human), location of 
rat cadavers in relation to 
(Manila), 162, 163 

importance of rapid diag- 
nosis of, 166 

biologic diagnosis of, 167 

a septicemic disease in all 
cases, 170 

symptomatology of, 171 
Pathologic considerations, 172 
Prognosis, treatment, conditions 
and, 173 



Plague, serum treatment of, 174 
symptomatic treatment, 174 
Prophylactic serum and anaphy- 
laxis, 177 
Plague vaccines, 178, 179 

Quarantine, modified, 56 
station, Mariveles, 59 
Quiapo, Manila, plague in, 63 

Rat fleas of Italy, 32 
of Brazil, 32 
of Great Britain, 32 
of United States, 32 
Rats, chronic plague in, 35 
subacute plague in, 35 
Requisites of the practical sani- 
tarian, 12 
Russia, plague in, 26 
Rats, wild, plague in, 29 

effect of seasonal conditions 
on, 34 
Rucker, Dr. W. C, 31 
Rosenau, Dr. M, J., 31 
Rat fleas, varieties of, 32 
of India, 32 
of Australia, 32 
Rat population of the world, 41 
destruction, economic impor- 
tance of, 42 
extermination methods, 43 
natural enemies of, 43 
destruction, bacterial viruses 
for, 43 
poisons used for, 43, 44 
trapping, 44 
traps, varieties, 45 
destruction by poisonous 
gases, 45 



190 



INDEX 



Rats, starving, 47 
Rat proofing, 48 

cost of, 49, 93 
infestation of ships, 50 
adaptability of, 51 
Rats, methods of entry of, 52 
Rat destruction by rat diseases, 

53 
Resistance of rat to diseases of 

bacterial causation, 54 
Rats and ground squirrels, chemi- 
cal poisoning of, 54 
Rat destruction by domestic ani- 
mals, 54 
catchers, house cats as, 55 
half wild cats as, 55 
terrier dogs as, 55 
on farms, terrier dogs 
as, 55 
Rapid diagnosis, importance of, 

56 
Rat cadavers, dispersion of fleas 
in Manila from, 65 
plague in Tondo district, 

Manila, 68 
proofing and rat destruction, 
72 
inapplicable at times, 73 
poisoning, trapping, effects 
of, 73 
Rats, birth-rate of, 73 
death-rate of, 73 
Removal of population in emer- 
gency, 74 
Rat plague in U. S. Army Com- 
missary warehouse, Manila, 
76 
fleas of Philippines, 78 
of Australia, 78 



Rat fleas of Italy, 78 

breeding as influenced by 

climate, 81 
in Javan "bale bale," 86 
in thatched roofs, 86 
dead, in bamboo house tim- 
bers, 87 
Rat catch, variations in, 88 
Rat catching methods, compara- 
tive statistics in, 89 
Rat catch and plague incidence, 

interpretation of, 91 
Rats, zoologic classification of, 

98 
Rat, ship, 99 
field, 99 
Rats, coloration of, 99 
Rat, Norway, 99 
gray, 99 
barn, 99 
sewer, 99 
Rats, unreliability of differential 
points in, 101 
conformation of skuUs in, 

101 
gnawing ability of, 102 
burrowing ability of, 102 
climbing ability of, 102 
jumping ability of, 102 
swimming ability of, 102 
Rat litters, size of, 102 
Rats as wire walkers, 103 
as rope walkers, 103 
Rat cadavers in Java, studies of, 
104 
time of death as indicated by 
postmortem changes of, 
104 



INDEX 



191 



Rats, postmortem changes in 
(Table), 105 
(illustration), 105 
Rat runs, notes on, 105 
nests, notes on, 105 
food, notes on, 105 
nests (Manila), breaking up, 
106 
Rats driven out with formalde- 
hyde gas (Manila), 106 
Rat killing with dogs (Manila), 

107 
Rat's nests in trees (Manila), 110 
Rat traps, snakes in (Manila), 
111 
swallowed by snake 
(Manila), 111 
Rats, collection and forwarding 

of (Manila), 122, 123 
Recovering plague bacilli from 

circulating blood, 134 
Roberg, Dr. David, 154 

Stability of virulence of B. pestis, 

36 
Spread of plague in recent years, 

23 
Suppression of plague, 40 
San Lazaro Hospital, Manila, 

13, 69, 161 
Schobl, Dr. Otto, 14, 29, 30, 76, 

96, 127 
Strong, Dr. R. P., 16, 36, 38, 59, 

135 
Sixth century, plague in, 20 
South America, plague in, ^, 26 
Siam, plague in, 25 
Suez, plague in, 22 
South Africa, plague in, 22 



Scotland, plague in, 22 

Sumatra, plague in, 25 

Straits Settlements, plague in, 25 

Simpson, Dr. W. J. 

Suctorial parasites in plague con- 
veyance, 33 

Seasonal conditions, effect on 
epidemics of, 34 
on rats of, 34 
on Bacillus pestis of, 

34 
on flea prevalence of, 
34 

Subacute plague in rats, 35 

Spontaneous abatement of 
cholera, 35 

Secondary plague pneumonia, 39 

Summary of prevention prob- 
lem, 37 

San Francisco, plague campaign 
in, 41 

Ships, fumigation of, 46 

Starving rats, 47 

Ships, rat infestation of, 50 

Summary of prevention for com- 
munity, 56 

Ship cargoes, disinfection of, 56 

Sick, isolation of, 56 

Steamer, Loongsang, 59 
Taisang, 59 

Spread of plague in Manila, 
favorable conditions for, 61 

Sleeping quarters, ground floor, 
72 

Swellengreble, Ph.D., N. H., 77 

Seasonal explanations of plague 
prevalence, C T 

Sanitary orders, Manila (garbage 
cans), 93 



V ,•',:- s. T.,'. '■ i, 



192 



INDEX 



Ship rat, 99 

Sewer rat, 99 

Sawah rat of Java, 100 

Swimming ability of rats, 102 

Size of rat litters, 102 

Simpson, surgeon, U. S. P. H. 

Service, 103 
Studies of rat cadavers in Java, 

104 
Snakes in rat traps (Manila), 111 
Snake, rat swallowed by 

(Manila), 111 
Specimen, sanitary orders, 116- 

121 
Sanitary Board (Hong Kong), 

the work of, 158 
Symptomatology of plague, 171 
Serum treatment of plague, 174 
Symptomatic treatment o f 

plague, 174 
Statistical studies in mortality, 

174-176 
Serum administration, dosage 

and technique of, 176, 177 

Types of plague, 30 

Treatment of plague, 165 

Turkey in Asia, plague in, 25 

Tarbagan, 28 

Teague, Dr. O., 38 

Terrier dogs as rat catchers, 55 

Terrier dogs as rat catchers on 
farms, 55 

Tondo district, Manila, rat 
plague in, 68 
human plague in, 68 

Taking charge of plague suppres- 
sive measures, Manila, 70 

Tondo, light material houses in, 
71 



Tondo, Manila, habitations and 
plague, 83 

Theatre disinfection, Manila, 93 

Time of death of rat as indicated 
by postmortem changes, 104 

Transmission of plague by blood- 
sucking insects, 137 

Trained bacteriologist, necessity 
for, 167 

Treatment, conditions, and prog- 
nosis, 173 
serum, of plague, 174 
symptomatic, of plague, 174 

Technique and dosage of serum 
administration, 176, 177 

United States Public Health Ser- 
vice, 26 
rat fleas of, 32 

Varieties of rat fleas, 32 

of rat traps, 45 
Variations in number of fleas per 

rat (Java), 78 
Van Loghem, Dr. J. J., 82, 84 
Variations in the rat catch, 88 
Vaccines, plague, 178, 179 
Vaccine, Haffkine, 178, 179 
Vaccines, combined, 179 

Widespread dissemination in re- 
cent years, 23 
West Indies, plague in, 29 
Wane of epidemics, 15, 35 
Work of Sanitary Board (Hong 
Kong), 158 

Xenopsylla cheopis in Java, 77 

Zoologic classification of rats, 98 



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